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The present paper is a report on the marine fishes observed and studied on my trip to the Caribbean coast of Colombia during August and September of 1949, for slightly over a month's duration. This was made possible by a grant in aid from the Eldridge Reeves Johnson Fund by the American Philosophical Society. Leaving New York by steamer on August 12 I sailed to Barranquilla, arriving August 18, after which I proceeded to Cartagena, which I used as a base until my return from Barranquilla on September 8. During this interval very interesting opportunities were afforded to visit the fish market at Cartagena. When the influx of fishes brought in was large, as in fair weather or under favorable conditions, it was possible to see great numbers daily, so that I made several trips at times. The number of species seen varied from 30 to 50. I seldom missed finding at least one or more species daily that I had not seen previously. The present paper is a report on the marine fishes observed and studied on my trip to the Caribbean coast of Colombia during August and September of 1949, for slightly over a month's duration. This was made possible by a grant in aid from the Eldridge Reeves Johnson Fund by the American Philosophical Society. Leaving New York by steamer on August 12 I sailed to Barranquilla, arriving August 18, after which I proceeded to Cartagena, which I used as a base until my return from Barranquilla on September 8. During this interval very interesting opportunities were afforded to visit the fish market at Cartagena. When the influx of fishes brought in was large, as in fair weather or under favorable conditions, it was possible to see great numbers daily, so that I made several trips at times. The number of species seen varied from 30 to 50. I seldom missed finding at least one or more species daily that I had not seen previously.

Rumex and Polygonum, of the family polygonaceae, occur in some abundance both in Colombia and in the United states, and this paper is an attempt to correlate a study of the Colombian plants with what has been observed in the United states. Through the courtesy of Dr. William R. Maxon, Curator, the facilities of the United states National Herbarium have been made available, and this work has been financed by the Wisconsin Alumni Research Foundation of Madison, Wisconsin. The writer's collections and field observations were made in Colombia from March to December, 1944, during such times as would not interfere with his work for the Colombian Cinchona Mission. Mr. E. P. Killip, Dr. F. R. Fosberg and Mr. Joseph Ewan have given me the benefit of their experience in South American botany to make a number of helpful suggestions.Rumex and Polygonum, of the family polygonaceae, occur in some abundance both in Colombia and in the United states, and this paper is an attempt to correlate a study of the Colombian plants with what has been observed in the United states. Through the courtesy of Dr. William R. Maxon, Curator, the facilities of the United states National Herbarium have been made available, and this work has been financed by the Wisconsin Alumni Research Foundation of Madison, Wisconsin. The writer's collections and field observations were made in Colombia from March to December, 1944, during such times as would not interfere with his work for the Colombian Cinchona Mission. Mr. E. P. Killip, Dr. F. R. Fosberg and Mr. Joseph Ewan have given me the benefit of their experience in South American botany to make a number of helpful suggestions.

The bird collection (52 species and subspecies) treated in this paper was collected in the upper Cusiana River, eastern slope of the Eastern Andes, Departamento de Boyacá, Colombia. In the introduction are given geographical details of the proper area where the material was secured. This study is very important because of the little knowledge on the ornisof the Eastern Andes in Boyacá. Some light is thrown on the similarities and discrepancies between the avifaunas of Boyacá and Cundinamarca (Eastern Andes) and also on the relations with the adjacent regions of Venezuela. The intergradation of Atlapetes semirufus zimmeri with A. s. semirufus is discussed and the subspecies Hemispingus frontalis flavidorsalis isadded to the colombian avifauna. Previous local avifaunas of the Andes in Boyacá are: Borrero and Olivares (1955) and Olivares (1963).The bird collection (52 species and subspecies) treated in this paper was collected in the upper Cusiana River, eastern slope of the Eastern Andes, Departamento de Boyacá, Colombia. In the introduction are given geographical details of the proper area where the material was secured. This study is very important because of the little knowledge on the ornisof the Eastern Andes in Boyacá. Some light is thrown on the similarities and discrepancies between the avifaunas of Boyacá and Cundinamarca (Eastern Andes) and also on the relations with the adjacent regions of Venezuela. The intergradation of Atlapetes semirufus zimmeri with A. s. semirufus is discussed and the subspecies Hemispingus frontalis flavidorsalis isadded to the colombian avifauna. Previous local avifaunas of the Andes in Boyacá are: Borrero and Olivares (1955) and Olivares (1963).

Some time ago Brother Nicéforo, a well known naturalist of the Instituto de La Salle, Bogota, Colombia, very kindly presented a small collection of birds from his country to the United States National Museum. Although small in number of both specimens and species, it appears to have been a "picked" lot containing a surprising number of records of interest, some of which were undoubtedly puzzling to the collector. It is this material that is here reported on. As may be noted in the body of this paper, not only is a form of tinamou, hitherto undescribed, made known to science, but the recorded geographic ranges of some thirteen other birds are hereby extended, including two additions to the recorded avifauna of Colombia. Some time ago Brother Nicéforo, a well known naturalist of the Instituto de La Salle, Bogota, Colombia, very kindly presented a small collection of birds from his country to the United States National Museum. Although small in number of both specimens and species, it appears to have been a "picked" lot containing a surprising number of records of interest, some of which were undoubtedly puzzling to the collector. It is this material that is here reported on. As may be noted in the body of this paper, not only is a form of tinamou, hitherto undescribed, made known to science, but the recorded geographic ranges of some thirteen other birds are hereby extended, including two additions to the recorded avifauna of Colombia.

This paper describes a new species of characid fish, Creagrutus nigrostigmatus, which differs from all earlier known species of the genus in possessing a well-marked black horizontal caudaI bar, as well as in the spacing of the teeth on the premaxillaries and several other characters, such as the laterally compressed head, the dorsal origin almost exactly midway between the snout and the, last caudal vertebra, on a vertical line slightly behind a vertical line through the pelvic insertions. The new species has hitherto been found only in the creek Pechilin, in the department of Bolívar in northern Colombia. The author states that this creek seems to possess a rather peculiar fish thorough fauna and recomends a investigation. This paper describes a new species of characid fish, Creagrutus nigrostigmatus, which differs from all earlier known species of the genus in possessing a well-marked black horizontal caudaI bar, as well as in the spacing of the teeth on the premaxillaries and several other characters, such as the laterally compressed head, the dorsal origin almost exactly midway between the snout and the, last caudal vertebra, on a vertical line slightly behind a vertical line through the pelvic insertions. The new species has hitherto been found only in the creek Pechilin, in the department of Bolívar in northern Colombia. The author states that this creek seems to possess a rather peculiar fish thorough fauna and recomends a investigation.

In continuation of my examination of the Neotropical Acanthocinini, the following paper contains description of eleven new species of the genus Lepturges Bates, with notes on another species. The genus Lepturges is one of the largest in the Tribe, and as many of the species are very small, probably many others remain unknown as yet. Fullkeys to the genus will follow in due course. In continuation of my examination of the Neotropical Acanthocinini, the following paper contains description of eleven new species of the genus Lepturges Bates, with notes on another species. The genus Lepturges is one of the largest in the Tribe, and as many of the species are very small, probably many others remain unknown as yet. Fullkeys to the genus will follow in due course.

In my recent paper on American Caecilians (Dec. 1942, Bull. Mus. Camp. Zool. 91, 6) the six then known specimens of Gymnopis from Colombia were regarded as of one species, G. nicefori Barbour, with a range from Cáceres in the Lower Cauca in northern Antioquia (alt. 150 m.) to Honda, Girardot and San Juan de Rioseco (alt. 1300 m.) in the Upper Magdalena valley. Later examination of four additional specimens from the Upper Magdalena valley, Honda (3) and Aguas Blancas in Tolima, seemed to confirm this view. It is therefore with some surprise that I find that a specimen of Gymnopis, taken by me at EI Centro, in the Central Magdalena valley, on Dec. 24, 1943, is not nicefori, and must be described as new. I name it in honor of my friend Wilfred Devereux Price, Esq., to whom I am indebted for kind assistance and hospitality at EI Centro. In my recent paper on American Caecilians (Dec. 1942, Bull. Mus. Camp. Zool. 91, 6) the six then known specimens of Gymnopis from Colombia were regarded as of one species, G. nicefori Barbour, with a range from Cáceres in the Lower Cauca in northern Antioquia (alt. 150 m.) to Honda, Girardot and San Juan de Rioseco (alt. 1300 m.) in the Upper Magdalena valley. Later examination of four additional specimens from the Upper Magdalena valley, Honda (3) and Aguas Blancas in Tolima, seemed to confirm this view. It is therefore with some surprise that I find that a specimen of Gymnopis, taken by me at EI Centro, in the Central Magdalena valley, on Dec. 24, 1943, is not nicefori, and must be described as new. I name it in honor of my friend Wilfred Devereux Price, Esq., to whom I am indebted for kind assistance and hospitality at EI Centro.

From Puerto Asís (Corregimiento de la Comisaría del Putumayo, Colombia) very few records of birds are found in the literature, but this paper treats 100 specimens representative of 39 species and subspecies collected there from June 26 to July 1st., 1964. Formicarius analis zamorae Chapman and Empidonomus a. aurantio-atro-cristatus (Lafresnaye and D'Orbigny) are new for the Colombian ornis. The present study combines the ornithological knowledge of Amazonian Colombia, Ecuador and Perú. From Puerto Asís (Corregimiento de la Comisaría del Putumayo, Colombia) very few records of birds are found in the literature, but this paper treats 100 specimens representative of 39 species and subspecies collected there from June 26 to July 1st., 1964. Formicarius analis zamorae Chapman and Empidonomus a. aurantio-atro-cristatus (Lafresnaye and D'Orbigny) are new for the Colombian ornis. The present study combines the ornithological knowledge of Amazonian Colombia, Ecuador and Perú.

In this paper a report is given concerning the distribution of some birds in the Colombian Amazonian and Orinoco drainages; also, some previous identifications are amended having at the present time more and better material recently collected and better facilities for studying. In addition, five new species. are recorded for the first time in the fauna of these regions and four new species and subespecies are added to the previous known list of Colombian birds. In this paper a report is given concerning the distribution of some birds in the Colombian Amazonian and Orinoco drainages; also, some previous identifications are amended having at the present time more and better material recently collected and better facilities for studying. In addition, five new species. are recorded for the first time in the fauna of these regions and four new species and subespecies are added to the previous known list of Colombian birds.

During the first four months of 1944 while the writer was engaged in exploration for sources of rotenone in Colombia, principally in the Eastern Llanos, some opportunity was found for general botanical collecting. Although both time and facilities for this purpose were limited to the extent that somewhat less than 500 numbers were obtained, these collections included a few undescribed plants and several species apparently not so far reported from Colombia. In addition to the two novelties described in the present paper, new species in the genera Axonopus, Grimaldia, Piper, Calolisianthus (genus new to Colombia), Hyptis, Bartsia, Castilleja, Alloplectus and Cephaelis will be described elsewhere by specialists in those groups, and new records for Lonchocarpus have already been published (Journ. Wash. Acad. Sci. 37: 111-113. 1947).During the first four months of 1944 while the writer was engaged in exploration for sources of rotenone in Colombia, principally in the Eastern Llanos, some opportunity was found for general botanical collecting. Although both time and facilities for this purpose were limited to the extent that somewhat less than 500 numbers were obtained, these collections included a few undescribed plants and several species apparently not so far reported from Colombia. In addition to the two novelties described in the present paper, new species in the genera Axonopus, Grimaldia, Piper, Calolisianthus (genus new to Colombia), Hyptis, Bartsia, Castilleja, Alloplectus and Cephaelis will be described elsewhere by specialists in those groups, and new records for Lonchocarpus have already been published (Journ. Wash. Acad. Sci. 37: 111-113. 1947).

This paper is a contribution to the knowledge of the avifauna of the Upper Magdalena River in Colombia. The birds, representative of 50 species and subespecies, were taken at Gaitania Municipio de Ataco, Tolima, a zone of humid forest on the eastern of the Central Andes (30) 8 N., 750 49' W. of Greenwich. Alt. 2100 m. approx.). This paper is a contribution to the knowledge of the avifauna of the Upper Magdalena River in Colombia. The birds, representative of 50 species and subespecies, were taken at Gaitania Municipio de Ataco, Tolima, a zone of humid forest on the eastern of the Central Andes (30) 8 N., 750 49' W. of Greenwich. Alt. 2100 m. approx.).

In this paper three species of the Phylum Chaetognatha (Krohnitta Pacifica, K. subtilis and Pterosagitta draco) are recorded by the first time from the Caribbean shore of Colombia. An statistical analysis is given for selected characters in P. draco. In this paper three species of the Phylum Chaetognatha (Krohnitta Pacifica, K. subtilis and Pterosagitta draco) are recorded by the first time from the Caribbean shore of Colombia. An statistical analysis is given for selected characters in P. draco.

The following paper continues the series of nomenclatural notes and adjustments commenced under the title "Studies in Neotropical Orchidology" in Acta Botanica Academiae Scientiarum Hungaricae, Vol. 14: pp. 63-70 (1968). As in the previous contribution, the genera considered in the present study are Brassavola R. Br., Schomburgkia Lindl, and HoffmannseggellaH. G. Jones. The notes which comprise this series of studieshave been accumulated during the course of collecting materials for a taxonomic revision of the three genera concerned.The following paper continues the series of nomenclatural notes and adjustments commenced under the title "Studies in Neotropical Orchidology" in Acta Botanica Academiae Scientiarum Hungaricae, Vol. 14: pp. 63-70 (1968). As in the previous contribution, the genera considered in the present study are Brassavola R. Br., Schomburgkia Lindl, and HoffmannseggellaH. G. Jones. The notes which comprise this series of studieshave been accumulated during the course of collecting materials for a taxonomic revision of the three genera concerned.

This paper is an attempt to interpret the negative isostatic anomaly of the Western Caribbean Sea on the basis of the new criterion used by professor M. Ewing et al. in their interpretation of the island arc in Pto. Rico area. The proposed interpretation is a departure from the previous one generally accepted, which was based on the tectogene theory of professor H. H. Hess. In other words, the negative anomaly is attributed here to the sediments' thickenning and possible geosynclinal structure, rather than to deeper tectogenic deformation involving sial and sima. A geomorphologic interpretation of the Caribbean continental shelf is offered on this basis. The interpretation is locally based on correlation of the isostatic anomaly values (pendulum) with surface gravimetric values (gravity meter) in the Colombian coastal area (near Barranquilla), as compiled by the International Geophysical Year's Colombian Gravity Committee, and general stratigraphic and structural data of the Atlantic coast. A brief account and analysis of gravimetric principles and previous gravity works and their interpretations is given, especially in connection with isostasy and the general island arc problem. The paper aims mainly at encouraging interest toward cooperative research and further geophysical detail work in the Western (Colombian) Caribbean. Sea area.

Se presenta una lista anotada de los mosquitos verdaderos, familia Culicidae, encontrados desde 1962 hasta 1966 en la zona del Río Raposo, en la Costa del Pacífico de Colombia, durante estudios sobre virus transmitidos por artrópodos. La familia está representada por 16 géneros conocidos previamente y otro nuevo para la ciencia. Estos géneros comprenden 87 especies con nombre. Para cada una se ofrece breve información sobre su método de captura, abundancia relativa y otros datos pertinentes. Las larvas o pupas de 41 especies conocidas se obtuvieron en diferentes tipos de criaderos. Por primera vez se registra en el país la presencia de 26 especies. De 4.727 grupos de mosquitos inoculados en ratones para buscar virus hay 116 aislamientos positivos que se diseutir an en próximos trabajos.We present here an annotated list of mosquitoes of the family Culicidae collected from 1962 to 1966 in the Río Raposo region of the Pacific coast of Colombia, in the course of studies of arthropod-borne viruses. There are included 86 named species of 16 previously known genera and one new genus and species being described in another paper. Forty-one species were reared from larvae and pupae collected in a variety of breeding places. Twenty-six species are recorded for the first time from Colombia. For each species, notes on the method of collection, relative abundance and other pertaining data are given. Viruses were isolated from 116 of 4,727 mosquito pools processed. These agents will be the subject of other papers to he published.

With this paper the following species and subespecies are added to the Colombian ornis: Nyctiprogne latifacia Phaethornis b. bourcieri Dendrocincla merula bartletti Gymnopithys leuscaspis lateralis Rhegmatorhina cristata Neopelma chrysocephalum Myiophobus roraimae Platyrinchus senex griseiceps Platyrinchus saturatus Hylocharis cyaneus viridiventris and Setophaga ruticila tricolora are registered for first time in the Cisandean region of Colombia; the presence of Trogon m. melanurus is confirmed in the country; 57 new species and subespecies are noted for the Comisaría del Vaupés in which territory the collection of birds studied in this publication was made. In that region of Colombia new localities were under survey, namely. Sabanas del Cubiyú and Caños Cubiyú and Negro of which a geographical and ecological description is given in the introduction. Previous publications containing geographical and ornithological information on the Vaupés are: Olivares (1955), Olivares and Hernández (1962) and Olivares (1964).

Obtention and purification of IgG by electrofocusing column anf its use as an antigen to elicite homologous antibodies in rabbits are presented in this paper. The advantages of this procedure are discussed.

The authors list 77 species and subspecies of birds collected on the Colombian bank of the Rio Negro, one of the larger northern tributaries of the Amazon. The Rio Negro, known as Guainía ("Huaynía") in the upper part of its course, forms the natural border of Colombia and Venezuela before entering the territory of Brazil. Of the birds listed, 74 were taken by Manuel Castro for the Coleccion ornitológica Phelps (Caracas, Venezuela), at San Felipe (opposite San Carlos, -Venezuela) and Macacuní (opposite El Carmen, Venezuela) in August-September, 1947. The authors also record the birds collected by Ernest G. Holt, Emmet R. Blake, and Charles T. Agostini in January, 1931, opposite San Carlos, Venezuela, i. e. San Felipe, Colombia. Among the nine species secured by these collectors three are not represented in Castro's 1947 collection. Sixteen birds are recorded as new to the avifauna of Colombia. The introduction of the paper mentions the naturalists who have explored the Rio Negro and the Guainía since Humboldt's celebrated voyage in 1800, and includes geographical notes, a map, and a brief description of the ecology of the region. Los autores enumeran 77 especies y subespecies de aves coleccionadas en la ribera colombiana del rio Negro, uno de los mayores afluentes septentrionales del Amazonas. El rio Negro, llamado Guainía ("Huaynía") en la parte superior de su curso, forma la frontera natural entre Colombia y Venezuela antes de entrar en territorio del Brasil. De las aves catalogadas, 74 fueron colectadas por Manuel Castro, expedicionario de la Colección Ornitológica Phelps, en San Felipe (frente a San Carlos, Venezuela) y Macacuní (frente a El Carmen. Venezuela) en agosto y septiembre de 1947. Los autores también hacen mención de las aves colectadas en enero de 1931 frente a San Carlos, Venezuela, es decir, en San Felipe, Colombia, por Ernest G. Holt, Emmet R. Blake y Charles T. Agostini. Entre las nueve especies conseguidas por estos colectores tres no figuran en la colección hecha por Castro en 1947. Dieciseis aves se registran por primera vez en la avifauna de Colombia. La introducción hace mención de los naturalistas que han explorado el río Negro y el Guainía desde el celebre viaje de Humboldt en 1800, y comprende una sucinta reseña geográfica acompañada de un mapa; con una breve descripción ecológica de la región.

1. The present paper includes studies about the Cranial Anatomy, Geographical Distribution and Ecology of Crocodylus intermedius in Colombia. 2. The material has been collected from the areas of the rivers Guaviare, Ariari, Güéjar and Cunimía. It consists of sixteen skulls and fifty-four fetus-containing eggs. 3. A detailed description of the skulls is given, the lengths of which range between 25.4 cm. and 70.7 cm. 4. Concerning the scalation: there is a single row of occipitals containing between 2 and 6 individual scutes: two rows of cervicals, the first containing 4 and the second 2 scales. The dorsals are in 16-17 transverse rows, the broadest of which contains 5-6 individual scales. The ventrals are in 25 to 27½ transverse, rows, the broadest of which contains between 14 and 18 individual scales. The tail has between 17 and 19 double-crested, and 17 to 19 single-crested segments. The scalation of 4 fetus does not show any special characteristics. 5. The coloration of Cr. intermedius varies between light-grey in juveniles and greyish green, light brown to yellowish in adults. The greenish color is due to the extensive growth of algae on the dorsal side. There are dark marks and spots on the entire dorsal and lateral sides as well as on the ventral side of the tail. The throat and belly are white and without marks. The colour of living specimens on sand banks, in bright sun appears almost white. 6. Cr. intermedius ranges, in Colombia, between the Rio Arauca in the east and the lower course of the Río Duda in the west. No intermedius are to be found in the rivers Vaupés. Caquetá and Putumayo (tributaries of the Amazon). In Venezuela he ranges as far as San Fernando de Atabapo in the upper Orinoco area. For unexplainable reasons he does not enter the Amazon, by the comunicatron of the Orinoco-Casiquiare-Río Negro. 7. Numerous ecological observations were made on habitat, size, alimentation, parasites, reproduction and behavior. The "record" in size is apparently shown by an old male, which, according to Humboldt was 22 feet 3 inches long (6.78 meters). As far as known the females do not grow larger than 4 to 4.50 meters. The 4 fetus were between 22.4 cm. and 23.7 cm. long. The food of intermedius consists mainly of fish: in the stomach specimens a great amount of small stones were found ranging from 440 gr. to 920 gr. The egg laying period takes place mainly in January and the juveniles hatch in March. The eggs are white; their average size is about 8 em. long and 5 cm. wide. Up to 70 eggs were found in a nest. March 3, 1957 a nest 43 cm. deep and 51 cm. wide at the base, was found in the Río Guaviare. It was situated on a, sand-bank, about 40 meters from the river. The first eggs were found in a depth of 27 cm. The temperature in the nest, measured before the eggs were taken out, was slightly higher than outside. The shell of the eggs was quite elastic while still in the nest, but became hard soon after being taken out. Of the 57 eggs found in the nest, 54 contained fetus, the remaining 3 were rotten. The fetus already moved; but still had a well developed vitelline sack. The female, a specimen a about 3 meters long, remained in the water, splashing furiously. Cr. intermedius undergoes an aestivation the dry season in the Llanos Orientales (Rivers Arauca, Meta, Vichada) but no information is available from the Guaviare area. The Orinoco Crocodile of the Guaviare area digs no subterranean caves as does Cr. acutus from the Magdalena region and other rivers of northern Colombia. Due to excessive hide-hunting Cr. intermedius was practically exterminated in large areas and became rather scarce even in remote regions. 1. Se presenta una investigación detallada sobre la anatomía craneal, distribución geográfica y ecología de Crocodylus intermedius en Colombia. 2. El material que forma la base para estos estudios, consiste en 16 cráneos y 54 huevos que contienen fetus, coleccionados en los ríos Guaviare, Ariari, Güejar y Cunimía en 1955-56 y 1956-57. 3. La descripción anatómica craneal fue hecha a base de cráneos de 25.4 centímetros a 70.7 centímetros de largo (tabla 2). 4. Se hicieron estudios detallados sobre el escamado, incluyendo el 4 de fetus (tabla 1). Existe una sola hilera de Occipitalia que contiene entre 2 y 6 escamas y dos de Cervicalia de las cuales la primera contiene 4 y la segunda 2 escamas. Los Dorsalia estan formados por 16 0 17 hileras transversales; el número de escamas en una de ellas es de 5 a 6. Hay 25 a 27½ hileras transversales de los Ventralia; el número de escamas en una hilera está entre 14 y 18. La cresta caudal doble contiene entre 17 y 19 segmentos, y la sencilla un número igual. 5. La coloración varía entre gris claro, verde y carmelita claro. Existen diferencias entre jóvenes y adultos. �� 6. La distribución geográfica abarca los territorios entre el rio Arauca por el oriente y el río Duda por el occidente. En el Vaupés, Caquetá y Putumayo afluentes del Amazonas no existe C. intermedius (mapa). En el Orinoco (Venezuela) se extiende hasta la región de San Fernando de Atabapo únicamente, pero no entra al Amazonas por el Casiquiare y el Rio Negro por razones aún desconocidas. 7. Los estudios sobre la ecología abarcan: Habitat, abundancia, tamaño, alimentación, parásitos, reproducción y costumbres. Se presenta una descripción del nido, los huevos y el fetus. 8. La caza comercial llevo a la extinción a C. intermedius en áreas extensas.

1. Se estudió la ovogénesis en la Hyla labialis para compararla con el mismo proceso en las ranas que viven en países con estaciones climatéricas definidas. Por inyección de glándula pituitaria se pueden obtener huevos fertilizados durante los meses de octubre a junio, y rara vez en los otros meses. 2. Se midieron y se contaron ovocitos enteros en muestras de ovarios maduros, inmaduros y después de la ovulación, Hay ovocitos de todos los tamaños presentes en los ovarios maduros; en los ovarios no maduros, y después de la ovulación hay células de todos los tamaños hasta 1.200 mm. de diámetro. 3. En secciones de ovarios se midió el diámetro de las células y de los núcleos y plaquetas vitelinas. Se estudiaron los cambios citológicos de los núcleos y también del citoplasma. Las plaquetas vitelinas aparecen en células que tienen un diámetro de 0.350 a 0.400 mm, La melanina aparece en ovocitos que tienen 0.700 mm. o más de diámetro. En general, los cambios citológicos son muy semejantes a los descritos por otros investigadores en otras especies. 4. La diferencia más obvia e interesante entre la ovogénesis de la Hyla Iabialis y la de otras especies descritas es la presencia de ovocitos de todos los tamaños y en cantidades grandes en el ovario inmediatamente después de la ovulación. Se piensa que los resultados demuestran que el proceso de ovogénesis sigue durante todos los meses sin detenerse como se hace en países con estaciones climatéricas definidas. 1. Oögenesis of the frog, Hyla labialis has been studied in order to Compare it with the same process in frogs which live in countries with definite climatic seasons. Fertilized eggs can be obtained after pituitary injection during the months of October through June and occasionally during the rest of the year. 2. Whole oöcytes were measured and counted in samples taken from mature ovaries, immature ovaries and ovaries after ovulation had taken place. There are oöcytes of all sizes present in mature ovaries; in immature ovaries and ovaries after ovulation there are cells of all sizes up to 1.200 mm. diameter. 3. In sections of ovaries, the diameter of the cells, of the nuclei and of the yolk platelets was measured. The cytological changes in the nuclei and cytoplasm were studied. Yolk platelets first appear in cells which have a diameter of 0.350 to 0.400 mm. Melanin is first found in cells of 0.700 mm. or more in diameter. In general, the cytological changes are similar to those described by other investigators for other species. 4. The most obvious and interesting difference between oögenesis in Hvla labialis and other species previously studied is the presence of oöcytes of all sizes and in large quantities in the ovaries studied immediately after ovulation occured. The results reported in this paper suggest that oögenesis is a continuous process throughout the entire year here in Bogotá, Colombia. In this respect it differs from that described for amphibians which live in countries with definite climatic seasons in which the growth of oöcytes is a discontinuous process and takes place in distinct groups of cells developing simultaneously.

From my studies on pediatric anatomy to be issued in the near future, I am interested in beginning its publication with a paper on the macroscopic anatomy of the thymus. In this chapter I shall try to describe the thymus, its form, size, most important anatomical relations, its irrigation, and innervation. Later on I hope to explain its embryology and its histology since its physiological role is being seriously investigated and is so far the subject of conflicting opinions. I shall abstain from comments, leaving this important chapter to be dealt with by biologists, pharmacologists and physiologists.