首页   按字顺浏览 期刊浏览 卷期浏览 The morphology of the chondrocranium ofGymnarchus niloticus.
The morphology of the chondrocranium ofGymnarchus niloticus.

 

作者: M. Omarkhan,  

 

期刊: Journal of the Linnean Society of London, Zoology  (WILEY Available online 1949)
卷期: Volume 41, issue 281  

页码: 452-481

 

ISSN:0368-2935

 

年代: 1949

 

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

 

出版商: Blackwell Publishing Ltd

 

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

 

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