ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1940.tb02414.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1940.tb02415.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1940.tb02416.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

SUMMARY.The chondrocranium of two larval stages ofGymnarchus niloticus—one 15‐day old, the other of an unknown but of slightly younger stage—have been studied. The morphological relations of the arteries, veins and nerves of the head have been described in detail, and the results have necessitated a rectification of some of the statements made by Assheton. The cartilage of the chondrocranium is greatly developed but conform to the general Teleostean type with certain peculiarities of its own. The larval skull is platytrabic. The auditory capsule is greatly developed and contains a modified ear and a sac‐like extension of the air‐bladder. The internal cavity of the capsule is divided by a partition which is partly ossified. In the lateral wall of the capsule is a vacuity covered by a membrane lateral to which extends the expanded portion of the temporal and supratemporal latero‐sensory canals. There is an extensively developed orbital cartilage with pre‐optic and metoptic roots and a pila antotica secundaria. The anterior and posterior myodomes are absent. All the eye muscles are collected in a fibrous orbital capsule. The internal carotid foramen is separated from the hypophyseal fenestra. There is no pro‐otic bridge, There is a well‐developed trigemino‐facialis chamber. A lateral commissure is present. Nasal capsules are practically absent except for a broad and massive internasal septum and a rudimentary lamina orbitonasalis. The pterygoquadrate is in a pro‐cartilagenous fusion with the hyomandibula. Neither otic, nor basal, nor basi‐trabecular articulations are present. The larval jaw suspension is methyostylic.Unique features inGymnarchusnot present in any known living teleost are: (1) presence of a pila antotica secundaria, (2) splitting of the common truncus hyomandi‐bularis of other fishes into more or less three separately originating nerves—n. mandibularis, n. opercularis superficialis, and n. hyoideus, (3) formation of an extra nerve, the dorsalis cutaneus facia

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1940.tb02417.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1940.tb02418.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1940.tb02419.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

Summary.Mucronella soulieriCalvet andLepralia asperrimaReuss are synonymous withCellepora pulchraManzoni.Manzoni's species belongs toHippopleuriferaCanu, a genus which appears to be related toUmbonulaHincks. The two genera may be referred to one family, Umbonulidae Canu, to be placed near the Petraliidae.Certain American Eocene and Oligocene species, described as belonging toHippomenella, appear to be more nearly related toHippopleurifera.They have been indicated by Stach as possible ancestors of the Petraliidac.Hippopleuriferais more or less intermediate in character between these Lower Tertiary species and the Petraliidae as represented byHippopetraliella.

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1940.tb02420.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY