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The intrinsic rate of increase of an animal population can be calculated from data on longevity, sex ratio, maturation rate and fecundity and can be expressed as r in the population growth equation Nt = N0ert. Laboratory and field data are used to calculate the value of r per day for the copepod Gladioferens imparipes Thomson. The r values obtained, 0.146 per day at 15� C and 0.293 per day at 25� C, are both high. This high population growth potential is interpreted as an adaptation to the estuarine habitat.

A new species of genus Labidocera, L. tasmanica sp, nov., found in the south-east inshore coastal waters of Tasmania, is described and figured. Its postnaupliar developmental stages are described and figured from the samples collected in the northern parts of D'Entrecastreaux Channel, Tasmania.

Population estimates of the king prawn, Penaeus plebejus, in Moreton Bay and adjacent offshore areas are made from a study of commercial catches and by tag-recapture experiments. Juvenile prawns which are abundant in Moreton Bay during the summer months rapidly migrate to adjacent offshore areas and form the basis of an offshore fishery. Population parameters for Moreton Bay are F1 = 0.04, E1 = 0.17 and M1 ≤ 0.22 week-1. For the adjacent offshore area the parameters are F2 = 0.02, M2 = 0.05 week-1. These estimates indicate that of the order of 17% of the available stock is caught in Moreton Bay and that of the order of 26% of the available stock is caught in the offshore area off Mooloolaba. From a yield equation the response in catch to variations in fishing intensity is estimated.

Breakdowns in the assumptions made by the Jolly (1965) method of estimating population size were detected in mark-recapture experiments with the western rock lobster. Using information gathered from sampling by both baited traps and by diving it was shown that, in particular, the assumptions of (1) a single population and (2) equal probability of capture of marked and unmarked rock lobsters, were not valid at all times in the 'population' studied, and this resulted in underestimates of population density. However, it was found possible to make suitable corrections to the raw data to arrive at apparently unbiased estimates of population density. In the cases studied, the calculated unbiased estimates of population density agreed well with unbiased estimates calculated from information gathered by marking and recapturing by different methods. Single census and the De Lury (1958) methods also grossly underestimated population density.

Thirteen species of the genus Portunus Weber are recorded from Australia, including one new species and five new records. These species are described and illustrated, and a key is given to known Indo-West-Pacific species. First pleopods of males are considered in detail and a key based on their features is included. The problems of designating subgenera are discussed and the relevance of a knowledge of the structure of first male pleopods is indicated.

The genus Austrochiltonia Hurley is rediagnosed and the two known species are fully redescribed and figured. Additional information concerning the distribution of these species is presented.

Growth in the eastern and western subspecies of this percoid fish is described and compared in a series of von Bertalanffy curves. While growth in the eastern subspecies is uniform throughout the area of its distribution, that in the western subspecies, with a much wider area of distribution, shows variation. Growth in the latter decreases with increasing distance from its spawning grounds in Western Australia, until at the eastern end of its range it is similar to that of the eastern subspecies inhabiting the same waters.

This paper deals with the results of the investigations of the Division of Fisheries, C.S.I.R.O., into the biology of the southern bluefin tuna (Thunnus thynnus maccoyii (Castelnau)), a representative in southern Australia and New Zealand of the tunny of Europe and the bluefin tuna of California. A comparative description of the morphology of the ,Australian form is given with a detailed study of its occurrence in Australia, including a discussion of the possible presence of local breeding stocks. The growth rate is considered from a study of length frequency data.' Considerable variations have been found in the growth rate of the younger age classes, as well as fluctuations in their relative abundance and their migratory movements along the eastern Australian coastline. Reference is made to the feeding habits in various areas.

The "commercial" scallop supports a dredge fishery in the D'Entrecasteaux Channel, Tasmania. There is probably a genetically homogeneous population in this area, and the juveniles possibly move from bed to bed, but the adult scallops form discrete, stable communities. The statistical history of the fishery reveals a marked decline in the availability of scallops since some time between 1941 and 1945. A more exact slatement cannot be made because fishing efforts in war time were not comparable in efficiency with those made before and since. Furthermore, before 1941 a second species of scallop was also fished, but not distinguished in the catch records. The rings in the shell are formed annually and can thus be used for age determination. This can be demonstrated directly in young scallops by comparing the growth at the edge of the shell at successive seasons of the year. In older scallops the growth increments are too small to compare in the same way; the evidence of the annual character of the rings is here mainly indirect, although in its totality convincing. There is distinct variation in growth rate between different beds, and apparent variation between different age-groups from the same bed. The age and size composition of the stocks were studied from samples taken from several representative beds from 1944 to 1949. The age composition studies showed that the year-classes produced in the period extending approximately from 1939 to 1941 predominated, and that very little recruitment had occurred since that period; the results of the size composition studies confirmed this. Scallop fishermen agreed that snlall scallops had been unusually scarce in the Channel for many years. It is concluded that the scallop population is suffering primarily from a severe long-term shortage of recruits, the cause of which, although apparently natural, is unknown; and secondarily from overfishing, as the fishermen exhaust, one after another, the aging, isolated subpopulations of adults on the different beds. Unless ample numbers of recruits soon reappear, the fishery may come to an end. (Since Mr. Fairbridge wrote this paper some beds of juvenile scallops have been located. Although the beds are not large, their presence indicates that the Channel population is still reproducing and that there could be a return to years of good recruit broods.)

This paper is a survey of all the known marine Chlorophyta of southern Australia, from the south-west corner of Western Australia to about the Victoria- New South Wales border, and including Tasmania. Full references to each species are given, all established synonomy, the type locality of each species and where the type specimen is deposited, and a summary of the known distribution. Critical notes on many species are given also.

Following a brief outline of the systematic relationships of a number of species comprising the Galaxias maculatus species complex, the morphology of the "landlocked jollytail", a lacustrine galaxiid from Lake Modewarre (south-western Victoria), is described and compared with that of the normally catadromous stream dwelling species G. maculatus and a number of other closely related forms belonging to this complex. The probable systematic status of the landlocked jollytail and its relationship to the other forms included in the G. maculatus species complex are then discussed in the light of both the above morphological evidence, and ecological and behavioural evidence from a previous study of the life cycle and discussion of the probable origin of this lacustrine form. The conclusion is drawn that the landlocked jollytail should probably be regarded as no more than an isolated "ecological race" of the normally catadromous stream-dwelling species, G. maculatus.

A new classification is proposed for the Australian Marginellidae, both Recent and Tertiary. Most previous papers and all Australian papers have previously referred to the many species under one genus Marginella, though occasionally they have been subdivided into several sections without generic names. This subdivision has now been carried farther, and the approximately 200 -Australian species have been divided into 33 genera, of which 31 are new and 2 have been recently named from Japan. Of the 33 genera 22 are Recent and 20 Tertiary, and 9 Recent and Tertiary genera are considered congeneric. Figures are shown of all the type species, and a key is provided to those still living in Australian seas. The second part of the paper reviews and figures all the known species from the Solanderian and Dampierian Zoogeographical Provinces. Species number 41, of which 33 are proposed as new. Of these, 37 are Solanderian and 9 Dampierian. Five species are common to the Solanderian and Dampierian and one to the Solanderian and Peronian, and one ranges through the Maugean, Flindersian, Peronian, Solanderian, and Dampierian Provinces.

New Australian Late Mesozoic species of Gymnodinium and Deflandrea (Dinoflagellata) and Odontochitina and Palaeotetradinium (Incertae Sedis) have been described. A new species of Wetzeliella from a South Australian Eocene deposit has thrown light on the taxonomic position of the genus. Hystrichokolporna cinctum Klumpp (Hystrichosphaeridae) has been recorded from Victorian Tertiary deposits.

This monograph incorporates a systematic revision of the freshwater mussels of the Australian Region (Australia, New Zealand, New Guinea and the Solomon Islands). Previous systematic works are revised and discussed. Details of the taxonomic procedures used in the present work are presented. One aberrant New Guinea genus, Haasodonta, with two species is referred provisionally to the family Unionidae Fleming, subfamily Rectidentinae Modell. The remainder of the Australasian species are assigned to the family Mutelidae Gray. Four subfamilies, Velesunioninae Iredale, Lortiellinae Iredale, Hyridellinae Iredale, and Cucumerunioninae Iredale, are recognized. These include eight genera, Velesunio Iredale, Alathyria Iredale, Weatralunio Iredale, Microdontia Tapparone Canefri, Lortiella Iredale, Hyridella Swainson, Cucumerunio Iredale, and Virgus Simpson. The genus Hyridella includes four subgenera, Hyridella s.s., Protohyridella Cotton & Gabriel, Nesonaia Haas, and a new subgenus for H. menziesi Gray. These eight genera include 27 species, three of which are polytypic. Three additional species are considered of doubtful validity and two nominal species are listed as nomina dubia. Each taxon is redescribed and all available data of shell morphology, soft anatomy, larval stages, distribution, and type material are presented. The distribution of the Australian and New Guinea species in relation to the fluvifaunal provinces of Iredale and Whitley is considered and a new name is proposed for the fluvifaunula of southern New Guinea. The evolutionary relationships of the Australasian freshwater mussels are discussed and it is suggested that, with one exception, they arose from a single ancestral stock and have subsequently differentiated into four subfamilies within this region. This view is supported by the close anatomical similarity between them.

Following allegations of a depletionary trend in the mullet stocks a conservation scheme was initiated in Western Australia in 1942 by raising the legal minimum length in successive stages. In 1946 the legal length reverted to that in force before 1942. As far as can be seen from the catch statistics, the stocks did not benefit by the restriction period, the catches being of the same order before and after. It is possible that an increase in stocks occurred in the Shark Bay area, but as the fishery in this region was under-developed prior to the inception of the scheme there is no data to confirm such a supposition. The course of the Shark Bay fishery should be closely watched for any signs of overfishing now that the stocks are being more fully exploited. It would appear that no alteration in minimum lengths will effect an increase in the mullet stocks of the estuaries. There has been a definite decline in the mullet population of the Swan River since the early part of the century. This could be due to environmental changes rather than an effect of overfishing.

Characters used in the taxonomy of pearl-shells are reviewed and their variation with age and environment is discussed. Extensive variations with age are revealed. The growth processes have proved to be the most distinctive and invariable criterion of species but are highly susceptible to erosion and mechanical damage. Other characters of major importance are the hinge teeth, general outline of shell, convexity, external markings, and internal shell margin. The soft parts are of little value in delineating species. Phylogenetic relationships within the genus are considered. It is held that the lingah type of pearl oyster is the most primitive. A key to the Australian species is given. On the basis of the review of taxonomic characters, 31 trivial names occurring in a check-list of Australian species are rearranged under six specific headings. These synonymies are discussed, the species redescribed, and the geographical ranges reviewed.

Teredicola typicus, previously known only from Hawaii, is reported from eight localities in Australia, two in New Zealand, and one in Japan. Hosts in Australia are Bankia australis, Teredo fragilis, and Teredo furcifera (all new for this copepod); in New Zealand, Bankia australis; and in Japan, Lyrodus pedicellatus. Incidence of the copepod in individual hosts is recorded and notes on its external anatomy are presented.

Recent extensive collections of freshwater sponges in Australia are subjected to a detailed taxonomic study. Of the 24 species now recorded, five new species are fully described and figured, and the taxonomic criteria of three hitherto rather dubious spongillids redescribed and illustrated. Full keys to the gemmule-producing genera of Spongillidae, and to the Australian species, are included. The environment and zoogeographical distribution of Australian spongillids are discussed.

Three further species, C. ultima (Brehm, 1960); C. canberra, sp, nov.; and C. clitellata, sp. nov., are added to the previous revision of the genus, and the description of another two species is completed. The discovery of C. ultima in the New Guinea HighIands is of considerable zoogeographical interest.

The genus, which now contains five species, is redefined so as to include a new subgenus. The number of previously described species is reduced from seven to four by synonymy. A new subgenus and species G. (Protogladioferens) symmetricus is described. A key to subgenera and species is given for both male and female specimens. All species are figured and described. General aspects of the ecology and distribution of the species are discussed.

The following new species are described and figured: Squilla granti from Moreton Bay, Queensland; S. terrareginensis from north Queensland; and S. meneilli from deep water off the New South Wales coast. Justifications are given for the elevation of S. scorpio var. immaculata Kemp 1913 to specific rank.

Experimental trapping of eels, using carrion-baited traps, was carried out on a number of rivers of various types throughout New Zealand. Where possible, a mathematical analysis has been applied to the trapping results and an estimate of the efficiency obtained. Total trappable population densities of between 30 and 1,368 lb./ac. Were found. An attempt has been made to correlate type of river with the population density. The amount of cover present is apparently the limiting factor. The baited trap takes very few eels of less than 24 in. long and is thus not a very efficient means of keeping a stream free from eels. The feeding habits of the eel are generalized and readily adaptable to most faunas. In most rivers trout occurred only infrequently in the stomach contents.

Barracouta is equal first with sea mullet in order of contribution by individual species to the Australian fish catch. The fishery is important only in Victoria and Tasmania, although the species is plentiful along the entire southern coast of Australia. From analysis of catch records, supported by observations on the fishery and the marketing situation, it is evident that there is no depletion. Variations in the Catch reflect principally the demand for the fish, which is usually below the catching capacity of the fishermen. At present the catch is being maintained at twice the pre-war level by a demand for fish for canning, largely for export. The influence of demand upon catch was remarkably shown in Tasmania during the war. There, in spite of opinions that the stocks were depleted, a four-fold increase in the annual catch was achieved, because of the demand and suitable control procedures. Barracouta was the only species in Australia which made a substantial contribution to the war-time demand for more fish.

Six species of potamonid crab, of which two are new, are described and illustrated. The zoogeography of the Australian potamonid fauna is discussed.

The main work consists of a systematic review of Indo-Pacific species of Didemnidae and their relationships, with comprehensive keys to their identification and distribution. Descriptions of 34 species taken from Australian waters are given; of these, eight species are new to science, and include a new genus containing two species. Larvae are available and described for most species for the first time. There is an introductory discussion on the phylogeny of aplousobranch families in relation to Didemnidae, and on the genera comprising the family, especially in relation to common cloacal systems and larvae. A small section is devoted to the geographical distribution of the species around the Australian coast.

The school shark fishery in south-eastern Australian waters has operated on a homogeneous stock which has a low reproductive potential. The species is slow-growing; the smallest mature males (120 cm) are over 8 yr of age and the smallest mature females (135 cm) are at least 2 yr older. The gestation period is approximately 6 months and it is estimated that only about half the female population bear young each year. Each gravid female carries 17-41 young with a mean number of 28. The lengths of the normal full-term embryos range from 280 to 350 mm with a mean for both sexes of 300 mm. The larger females tend to have the longest embryos. Slightly more male than female young (54 : 46) are born. Because the inshore populations of juveniles have been dwindling and the size of the older stock is decreasing, it is believed that this slow-growing species is being overfished. Measures aimed at protecting school sharks in their vulnerable stages have been proposed. Any conservation programme will be long-term as this shark has such a low reproductive capacity.

Of 20,128 fish of 29 species tagged, 9.4 per cent. were recovered by commercial fishermen and anglers. A further 1.5 per cent. were retaken by the tagging crew. Only 11 species were tagged in numbers greater than 100. Returns covered 17 species, showing recovery rates varying from 1 to 21 per cent. Some exchange of fish takes place between the northern and southern parts of the lake, but this is consistent only in the case of the flat-tail mullet. Within the two parts of the lake lateral movements of some species take place; other species are sedentary. These facts suggest that the necessary condition for population estimation, that tagged fish should be randomly distributed amongst the population, is not achieved for most species.

In Australian waters the stock of Australian "salmon", a percomorph form, is composed of two clearly defined populations. These populations are referred to as the eastern and western subspecies. The western subspecies is normally the only group found in Western and South Australia, whereas the eastern subspecies is normally the only group found in New South Wales. The distributions of the subspecies overlap in Tasmania and Victoria. The subspecies differ in the number of rakers on the first gill arch; the western subspecies has 25-31 rakers, the eastern subspecies 33-40. The number of gill rakers can be related to the mode of feeding as the predominant food of the western subspecies is the pilchard, Sardinops neopilchardus (Steindachner), while that of the eastern subspecies is the euphausiid, Nyctiphanes australis Sars. Small but significant differences are evident in the number of rays in the dorsal fin, and in the number of scales around the girth.

Different populations of barracouta (Scombriformes: Acinaceidae), the principal Australian fish of commerce, have been recognized by a study of differences in the following: spawning season; size composition of adult stock; and seasonal movements and annual fluctuations as revealed by records of catch and fishing effort. Tagging experiments gave little information because of the low rate of commercial exploitation of the populations. There are probably five populations in southern coastal waters, which make migrations to certain areas as follows: one in winter and spring to eastern Victoria and southern New South Wales, one from spring to autumn to Bass Strait and its western approaches, one in summer and autumn to eastern Tasmania, one in autumn and winter to South Australia and western Victoria, and one (possibly not distinct from the previous population) in autumn and winter to the south coast of Western Australia. Spawning and feeding take place in the course of these migrations. Little is known about the populations when they are not migrating, but the three first-mentioned groups all appear to seek the neighbourhood of eastern Bass Strait between the migratory seasons. The fish prefer waters of about 13-180C and tend to vacate areas when they become cooler or warmer than this. Only the Bass Strait and eastern Tasmanian populations are significantly fished and the size of the catches is generally governed by the demand. However, there have been occasional years of scarcity, such as 1950-51 and 1951-52 in Bass Strait and 1951-52 in eastern Tasmania. These represent natural fluctuations (there is no evidence of depletion of any population) and for the Bass Strait population they are probably fluctuations in availability in the fishing areas rather than in abundance of the whole population. It is considered that the combined Australian populations could yield 10 times as much as the present annual catch of 6,000,000 Ib (beheaded and cleaned) when fluctuations were not adverse.

The taxonomic utility of various characters is discussed. The status of Hemiboeckella searli Sars is discussed, and the retention of the monotypic genus Hemiboeckella is considered to be justified. A list of generic characters is given for both Boeckella and Hemiboeckella, a key is given to the Australasian species of Boeckella and is accompanied by comparative drawings. Except for B. minuta Sars, this key does not enable female specimens to be identified. The number of Australasian species of Boeckella previously described is reduced from 25 to 14 by synonymy. Two new species, B. geniculata and B. montana, and a new subspecies, B. robusta maxima, are described. Another apparently new species is figured but not named (based on a single specimen only). Two species described from New Zealand are recorded from Australia for the first time. The male fifth legs of all species are described and, except for B. opaqua Fairbridge, all are figured. Additional features are also figured for some species. The distribution of species and some general aspects of their ecology are discussed.

The yellow-eye mullet scale is of the typical percomorph type, feebly ctenoid in most cases, but cycloid in the mid-flank region, which provides the best scale for age and growth determinations. The annual "break" is more obvious in the posterior sector than in the anterior. Above a length of 5 cm (length to caudal fork) there is a straight-line relationship between increments in dimensions of scale and increments in length of the fish. The scales of Victorian and Tasmanian fish are smaller than those of Western Australian fish, which is in accord with the rather larger number of scales in eastern fish. The annual "breaks" become apparent in spring when growth recommences after the winter cessation. As western fish are winter spawners and eastern fish summer spawners, the age and size attained at the time of formation of tho annuli differs in the two stocks. Females grow faster than males. Lengths (cm) attained each winter average as follows: Year I II III IV V VI VII Western fish 11 18-19 24-25 29-32 32-35 38 39 Eastern fish 5 12-13 19-21 24-27 30 The Petersen method of modal progression gives rather higher readings in the first and second years, probably as a result of mesh selection.

Samples collected from 62 sites within c. 1½ sq miles by means of a van Veen grab contained a small number of species (animal and plant), dominated by two species of ophiuroids. Without sophisticated analyses it is possible to delimit obvious "communities" based on dominants and subdominants, for example an Amphioplus- Amphiacantha community and a soft coral-sponge community. Similarly areas of high species diversities can be identified, these conforming approximately with the recordings of species occurring in single sites. Further analyses were made numerically after transformation of the data using the Bray and Curtis (1957) measure of affinity and the Lance and Williams (1967b) system of flexible sorting. Nine site groups were derived and ordinated by the "principal co-ordinate analysis" of Gower (1966, 1967). These groups were reduced to eight by detailed consideration of site characteristics. A gritty area is characterized by epifauna (soft coral and sponge), a "clean" area by a tubicolous polychaete Mesochaetopterus, and six areas by the two ophiuroids Amphioplus and Amphiacantha. Amongst these the following can be distinguished from a western to eastern (seawards) direction: (a) low numbers and patchy distribution of both ophiuroids and virtually nothing else, (b) both ophiuroids with a bivalve mollusc Tellina and a stomatopod Clorida, (c) moderate numbers of both ophiuroids, (d) large numbers of Amphioplus with moderate numbers of Amphiacantha and three associated species, and (e) two areas which are essentially ecotones of the last. The "associations" are compared in detail with others involving comparable genera. While it was expected that in these warm waters there would be a heterogeneous biota with indefinite "community patterns", as just indicated the situation was relatively simple. Data were of such complexity to be ideally suited for a comparative study of methods of numerical analysis, and these are outlined in the Appendix. Three standard models were used, two of which were discarded. After prior transformation of the data (including elimination of species with a single occurrence and fusion of sites in proximity) the final technique proved satisfactory.

The pale-coloured "white" marine crayfish which occur seasonally along the southern part of the Western Australian west coastal shelf are recently moulted immature crayfish, and are stages in the development of the Western Australian commercial crayfish Panulirus longipes. It is suggested that individuals which reappear as whites the following season have failed to mature in the intervening period. During these phases, the average annual increment is about 0.3 in. in carapace length. Crayfish in this phase had carapace lengths from 2 3/8 to 3 3/4 in.

The species composition and general ecology of intertidal organisms present at Heron Island, a coral cay in the Capricorn Group, are recorded in this paper. It was found that the general zonation picture on this Great Barrier Reef island differed markedly from that found previously at localities on the Queensland mainland (Endean, Kenny, and Stephenson 1956). In particular the mainland upper barnacle (Chthamalus) zone was not represented at Heron I., and the species forming the mainland lower barnacle zone (Tetraclita squamosa (Bruguiere) ) was replaced by a different species (Tetraclita vitiata Darwin). Also the characteristic algal zone of mainland localities was replaced by a lithothamnion-zoanthid-coral zone. In order to investigate the possibility of a gradual transition from the mainland type zonation to that found on the Great Barrier Reef, as exemplified by Heron I. zonation, the species composition and general ecology of intertidal organisms inhabiting a series of continental islands lying off the Queensland coast between lat. 16� and 22� S. were investigated. The fauna of these islands was found to be closely allied to that of the mainland. There was, however, an intrusion of corals and zoanthids on the more exposed of the islands visited which lie between lat. 20� and 22�S., and also on the more northerly of the islands visited. The biogeographical implications of these findings are discussed, and it is noted that the results of the present investigation support the contention of Whitley (1932) that a longitudinal division of the Queensland marine fauna into "Solanderian" and "Banksian" elements is warranted. Accounts are also given of the major environmental factors that might affect specific composition and zonation patterns at the localities investigated. Analyses of these have given much information on the general ecology and distribution of many Queensland intertidal species. Thls information is discussed. Of particular interest was the finding that the Peronian barnacle Tetraclita rosea (Krauss) has extended its range,to the north of the biogeographical boundary situated near lat. 25� S. by colonizing the more exposed of the continental islands.

An account is given of a collection of 85 species of simple ascidians from all parts of the Australian coast, including descriptions of 23 species new to science. Comprehensive keys for all species already described from the Australasian area accompany the account of each genus. There is a short discussion on the distribution of simple ascidians in Australia; and the Baudinian region, a new zoogeographic marine region in south Western Australia is proposed.

This paper reviews for the first time the family Pyramidellidae from northern Australia. The area includes the Solanderian zoogeographical province, and part of the Dampierian province. All species, whether previously described or now proposed as new, are figured and discussed. The division of the family into three new subfamilies is also proposed. In all 150 species or probable species belonging to 40 genera are reviewed. Of the genera 15 are proposed as new, and of the species 90 are proposed as new, and seven are left specifically unnamed pending the acquisition of more material. A key to the subfamilies and Australian genera is provided.

This paper deals with the Australian sipunculids of the genera Sipunculus, Xenosiphon, and Siphonosoma. Sipunculus angasi Baird, 1868, a species allied to S. nudus and S. robustus, is redescribed from south, south-eastern, and eastern Australia. A sipunculid from New South Wales is redescribed and assigned to the genus Xenosiphon. Siphonosoma cumanense (Keferstein 1867) and Siphonosoma vastum (Sel. and Biil. 1883) are redescribed from Queensland and Western Australia.

Descriptions are given of the reproductive cycles of five marine species of mussels. Two of these species have a southern Australian distribution and three are tropical Indo-Pacific species or have Indo-Pacific affinities. The reproductive cycles differ significantly, each species exhibiting a characteristic breeding pattern. A distinction is drawn between the season of gametogenic activity and the much narrower season of actual spawning. In four of the species the major features of the reproductive cycle correlate with latitudinal distribution. This is interpreted as evidence supporting the role of temperature as a principal determining factor in the control of broader aspects of the reproductive cycle (i.e. duration and season of gametogenic activity). Differences in finer details of the reproductive cycles (e.g. spawning season and number of spawning peaks) appear to be controlled by unknown factors besides temperature.

This paper deals with the following genera of Australian sipunculids: Phascolosoma, Dendrostomum, Golfingia, Aspidosiphon, and Cleosiphon. Nineteen species are recorded, of which Phascolosoma rottnesti from Western Australia, Phascolosoma dunwichi and Phascolosoma heronis from Queensland, and Dendrostomum cymodoceae from South Australia are new. Phascolosoma scolops var, tasmaniense has been given specific rank as P. tasmaniense. Two new subspecies, Golfingia margaritacea adelaidensis from South Australia and G. vulgaris queenslandensis from Queensland, are also described. A key to the Australian genera and species is given.

In a previous paper the catch statistics of the east Australian trawl fishery (Fairbridge 1948) were discussed, and in the present work, the biology of the most important species, the tiger flathead, is examined in greater detail. An age determination technique is developed for this species, and the age composition of the catch of recent years is analysed. The sampling technique carried out at the Sydney Fishmarkets is described and tested. The results are given of the first experimental trawling in Australian waters using a fine-meshed cover on the codend. The biology of the species is studied, chiefly from the point of view of establishing the age determination technique and the final analysis of the catch. Spawning is protracted, lasting throughout the six warmer months, and takes place throughout the geographical range of the species. The males spawn first in their second year, the females in their third or fourth. The "condition" (K) of the gutted fish is lowest in February, after spawning. It is probable that there is a single, genetically uniform stock, with a single centre of maximum occurrence. The younger age-groups probably do not undertake extensive coastwise movement; as a result, local areas are liable to become relatively depopulated by heavy fishing. The method of collecting and reading the flathead otolith is described. The otolith is found to grow isauxetically above a fish-length of 10 cm., and the technique of back-calculation is therefore used as an aid in age determina- tion. The otolith in this species is certainly not as clear to interpret as that of the North Sea plaice, but is probably comparable with that of the cod or hake.

Recent collections from Australian waters have contained four new species which are described and, in addition, seven species not recorded previously, five of which have merited full description. In addition the known ranges of several Australian species have been extended, including 14 new records for Western Australia. Minor comments on structure and coloration of certain species are also given.

This paper continues previous ecological studies (Dakin, Bennett, and Pope 1948) of the intertidal zone of south-eastern Australia. The environmental factors and the zonation of the animals and plants on the exposed rocky coasts of Victoria are described. As a result of this survey a rearrangement of the biogeographical provinces of the Australian littoral is made, and a new Cool-temperate fauna and flora are recognized on the coast of Victoria.

The evidence of taxonomic differentiation in the Australian pilchard is reviewed. Three major groups (called races), located respectively in eastern, south-eastern, and south-western Australian waters, are distinguished by differences in growth rate. The boundary zone of the two former is near the New South Wales-Victoria bolder, but it is not certain to which of the two latter races the South Australian fish belong. The two former races are sukdivided into smaller, more or less separate stocks (populations), which are distinguished mainly by differences in mean number of vertebrae and in abundance fluctuations. There are at least two such groups in the eastern race, which meet between Port Jackson and Jervis Bay, and at least two in the south-eastern race. The pilchards of Cook Strait, New Zealand, are probably distinct from those of any Australian locality.

The species Diaptomus (Eodiaptomus) lumholtzi Sars and D. (Tropodiaptomus) australis (Kiefer) are redescribed and figured. Both species are recorded from numerous new localities in northern Australia. The southern limit of distribution of D. lumholtzi is discussed in relation to the northern limit of Boeckella. A single example of the coexistence of D. lumholtzi with Boeckella triarticulata, and three examples of coexistence of D. lumholtzi with Calamoecia are cited.

Two main river systems are included in this region, the Derwent and the Huon. Data derived from anglers' returns are analysed for each system separately but those from the Huon are insufficient for a thorough study. There is some doubt as to the representativeness of returns from either system. No significant changes have been found in the fishery over a period of 12 seasons either in the rate of daily catch per angler or in the length of fish taken. A study of the fish taken in an upstream trap at spawning time yields an annual mortality rate of about 60% for the Derwent River System and recaptures of tagged fish show a similar rate. Population estimates based on recaptures of tagged fish and on the spawning potential within the system indicate a total population of between one- half and one million, of which about 20% is of takable size. The contribution made by the release of hatchery-reared fish is shown to be insigniiicant. Evidence is produced which leads to the conclusion that there may be two distinct races of trout in Tasmania, the result of separate introductions of river and sea trout, distinguished by inherent meristic differences as well as by differences in growth rate and habits.

A year's survey of the fauna and flora present in a freshwater pond provides the first work of its kind recorded in New Zealand. Attention was given to the effect of the recorded chemical and physical factors on the fluctuations in number of the zooplankton. A comparison of the local phytoplankton and zooplankton with those from similar studies in North America, Europe, and Asia shows the cosmopolitan nature of the inhabitants of freshwater.

Two new species of the genus Parisia Holthuis are described (P. gracilis, sp. nov., and P. unguis, sp. nov.). The relationships of these species to each other, and to the previously described species of the genus are discussed. The relationships of the species of Stygiocaris Holthuis are considered, and the occurrence of freshwater subterranean decapods in Australia is discussed in general terms.

The 12 species of Charybdis known from Australia, including two new records, are keyed and illustrated. First pleopods of the males are considered in greater detail than in past works, and a key based on their features is included. Minor changes in Leene's (1938) synonymy are proposed.

Changes in the gross morphology and histological structure of the gonads of a landlocked form of Galaxias maculatus inhabiting Lake Modewarre, south-western Victoria, are described in relation to the seasonal pattern of gonadal maturation outlined in a previous paper on the life history of this fish. Macroscopic changes in the gross morphology of the gonads are classified as to seven arbitrary maturity stages, these approximately corresponding, in the case of the male, with seven histological stages of testicular development. Nine stages of oocyte development in the ovaries of female fish are also outlined, and a single case of synchronous abnormal hermaphroditism is described. The above findings are then discussed in relation to those of previous studies on the gonads of a variety of teleost fishes, and in particular a number of other forms also belonging to the order Salmoniformes.