中国鲨类脑颅的研究

本文解剖观察了我国有代表性的鲨类脑颅共32种,分隶于8目14科24属。研究结果认为鲨类的脑颅共可分为9个式型和12个亚型。现存虎鲨目、须鲨目的鲸鲨科和扁鲨目吻软骨缺如,六鳃鲨目、须鲨目、角鲨目和锯鲨目均具一吻软骨,它们是一些古老和一些特化的类群。现存大多数种类均具3根吻软骨。在各不同分类阶元常有其不同的形态特征,可作为分类依据之一,亦可显示其亲缘关系。

A STUDY ON THE NEUROCRANIA OF SOME CHINESE SHARKS

This paper presents a comparative study on the neurocrania of 32 representative species of sharks of China, belonging to 24 genera, 14 families and 8 orders.According to the different morphological characters of neurocrania in different groups of Seiachomorpha, 9 patterns and 12 subpatterns are divided. A key to the patterns of neurocrania of the Chinese shark orders and families is given.In Palaeozoic Cladoselachc fyleri (Cladoselachii) the rostral cartilage is absent, and in Xe-nocanthus decheni (Xenacanthii) there is one rostral cartilage. In extant Heterodontidae, Rhin-codontidae and Squatinidae the rostral cartilage is also absent. In Hexanchidae, Orectolobidae, Squalidae, Pristiophoridae there is one rostral cartilage. Other families have 3 rostral cartilages Families without rostral cartilage or with one rostral cartilage are considered to be primitive or specialized groups.Neurocrania of Rhincodontidae and Squalidae belong to the Squatina pattern. Nostrils and mouth of these sharks are nearly terminal, snout short and eyes small. The similarity of their neurocrania is considered to be a case of convergence.Galeorhinus japonicus was placed in the family Carcharhinidae by some writers, but according to the form of supraorbital shelf, it is referred to the family Triakidae by the present authors.