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AbstractThe section in the lower middle Cambrian Thorntonia Limestone one kilometre south of Thorntonia Homestead, described by Whitehouse (1940, 1941), has been re-investigated using acid-etching techniques. Thousands of variously silicified bioclasts etched from this section are the basis of this study. The echinoderms CymbionitesWhitehouse, 1941 and PeridionitesWhitehouse, 1941 are shown to be basal circlets of stalkless, multicirclet, epispire- and brachiole-bearing eocrinoids. These two genera appear most closely related to LichenoidesBarrande from the Czech Republic. A stalked eocrinoid, Thorntonites dowlingigen. et sp. nov., and an edrioblastoid, Ikerus edgarigen. et sp. nov., occur with Peridioniteshigher in the section than Cymbionites. Thorntoniteshas a multimeric stalk and fused conical holdfast, at least three circlets of thecal plates with fewer and coarser epispires, and larger brachioles around the summit. Ikerushas a multimeric stalk, three circlets of thecal plates and straight ambulacral grooves, without connection to the thecal interior, traversing the central axis of thecal plates. These three eocrinoids and the edrioblastoid occur in shallow-water carbonates as abundant, low-to-medium tier, suspension feeders associated with brachiopods, molluscs, hyoliths, sponges, edrioasteroids and trilobites. This associated fauna includes Xystriduracf. negrina, Xingrenaspiscf. tongshanensis, Diraphora dyunyin, Westonia nyapungensis, Latouchella accordionataand Guduguwan hardmani, which collectively allow correlation with the Xystridura negrinaassemblage.*Peter A. Jell [amjell@bigpond.com], School of Earth Sciences, University of Queensland, St Lucia, Queensland 4072, Australia; James Sprinkle [echino@jsg.utexas.edu], Department of Geological Sciences, Jackson School of Geosciences, University of Texas, 1 University Station C1100, Austin, TX 78712-0254, USA.

Cook, A.G. & Jell, P.A., September 2015. Carboniferous platyceratid gastropods from Western Australia and a possible alternative lifestyle adaptation. Alcheringa 40, XX–XX. ISSN 0311-5518Platyceratid gastropods, common and in many cases abundant as elements of middle Palaeozoic gastropod faunas worldwide, are rare or absent in Australian Devonian faunas. In Australia, the earliest abundant platyceratids occur in the Lower Carboniferous (Tournaisian) echinoderm-rich Septimus Limestone and Enga Sandstone in the Bonaparte Gulf Basin, Western Australia. Four taxa, each with significant morphological plasticity, are recognized. In Platyceras(Platyceras) tubulosus(de Koninck, 1883), three rows of long radially arranged spines and common pentameral symmetry of re-entrants on the aperture suggest an alternative possibility that a relationship between echinoderms and platyceratids developed, and that this may be with archaeocidaroids that are commonly preserved with the gastropods. Similarly in the singly spinose Platyceras(Platyceras) emmemmjaesp. nov., re-entrants suggest an echinoderm relationship. It is proposed that an echinoderm–Platycerasrelationship possibly developed in Australia only after a suitable echinoid host had evolved allowing an alternative way for a gameto- or coprophagous habit to be exploited fully.Alex G Cook [alex.Cook@y7mail.com] and Peter A. Jell [p.jell@uq.edu.au], School of Earth Sciences, The University of Queensland, Queensland 4072, Australia.

RAVEN, R.J., JELL, P.A. & KNEZOUR, R.A., 9.02.2015. Edwa maryaegen. et sp. nov. in the Norian Blackstone Formation of the Ipswich Basin—the first Triassic spider (Mygalomorphae) from Australia. Alcheringa 39, 000–000. ISSN 0311-5518Edwa maryaegen. et sp. nov. is described as the first fossil diplurid mygalomorph from Australia and the fourth Triassic mygalomorph worldwide. Other fossil diplurids are reviewed: Edwagen. nov. is included in the Masteriinae; CretadipluraSelden, DinodipluraSelden are transferred to the Euagrinae along with Seldischnoplura seldenigen. et sp. nov., which had been originally assigned to Dinodiplura ambulacraSelden.Robert J. Raven [robert.raven@qm.qld.gov.au] Queensland Museum, GPO Box 3300, South Brisbane, Queensland, 4101, Australia; Peter A. Jell [p.jell@uq.edu.au] School of Earth Sciences, University of Queensland, St Lucia, Queensland, 4072, Australia; Robert A. Knezour [annandrob@optusnet.com.au] 14 Glebe Road, Newtown, Queensland, 4305, Australia.

A small millipede with distinctive tergal ornament is described from the Westgrove Ironstone Member in the upper part of the Early Jurassic Evergreen Formation in the Surat Basin, Queensland. Its taxonomic placement within the class is uncertain at present as the species displays characters of two orders and is incompletely known. It is the first description of fossils of the class Diplopoda from Australia. The material, consisting of two poorly preserved incomplete individuals is described as Decorotergum warrenae gen. et sp. nov.

Two species of arthropods are described from the earliest Ordovician (Lancefieldian, La 1) Zone east of Lancefield in central Victoria some 60 km north of Melbourne. Corcorania trispinosa gen. et sp. nov., with three prominent anterior head spines, seven trunk segments, a short distinctive posterior shield and large spinose appendages, is apparently unrelated to any previously known arthropod, fossil or living, and represents a new family (Corcoraniidae). Similarities between a small specimen of Corcorania and Mollisonia from the Burgess Shale are noted but no phylogenetic position for Corcorania is proposed. Caryocaris stewarti sp. nov. is described as a new phyllocarid distinguished by the various spines of its carapace and by the shape of its furcal rami.

Four different types of structures on fossil arthropods are shown to have been grouped under the term 'genal caeca'. These are distinguished and the most conspicuous (i.e. the fine radiating cephalic ridges of trilobites that anastomose repeatedly before joining a major ridge in the border) are interpreted as the external representation of auxiliary respiratory systems at least in some Cambrian genera. A number of possible functions are considered for these ridges and none but respiration is found to be feasible. Supportive evidence for the hypothesis outlined is drawn from consideration of the paradigm for a dorsal respiratory system and from a comparison with living crustacea.

The acid insoluble sclerites of Thambetolepis delicata gen. et sp. nov. of late Tommotian or immediately post-Tommotian age from near Ardrossan, South Australia, are described. These sclerites, as well as those of Sachites Meshkova 1969 and Halkieria Poulsen 1967, are from multi-sclerite animals similar to Wiwaxia Walcott 1911 together with which they constitute the new class Thambetolepidea. Biological affinities of these fossils are discussed in the light of the complex internal structure of the sclerites. Possible assignments to the opisthobranch gastropods, the polyplacophorans, or the annelids are discussed but the taxonomic position of Thambetolepis and the Thambetolepidea is unresolved.