71 THE SKULL OF AMIURUS— KINDRED 



INTRODUCTION 



The study of the development of the teleost skull has been confined for 

 the most part to isolated stages and there have been very few papers dealing 

 with the changes which take place in any one species. Parker's (1872) work, 

 on the development of the cranium of Salmo has remained the standard and 

 has been supplemented by Gaupp (1902) and Schleip (1903). Winslow (1897) 

 describes the chondrocranium of the trout, Ryder (1886) and Pollard (1895) 

 the chondrocrania of some of the Siluroids, but none of these attempted to 

 trace the formation of the bones and their relation to the cartilage, in the 

 same way that Parker did. Swinnerton (1902) has described several stages in 

 the development of the skull of Gasterosteus. 



The skull of the adult teleost has been widely studied in a topographical 

 way, but very few authors have analyzed the bones in terms of their develop- 

 mental relations, so that a wide field is open for this line of investigation. 

 Gouan (1770) gives a simple account of the bones of the cranium and naively 

 states that although there are many bones in the cranium of the yoimg fish, 

 these fuse into several large bones in the adult, as in man. Many of the 

 names in use in the terminology of the present time have come directly from 

 Cuvier, but others have been introduced into the literature principally by 

 Owen (1848), Huxley (1864), and Parker (1872). Except for a few scattered 

 references to the cranium of Silurus glanis, Clarias, Auchenaspis, and the 

 incomplete description of the cranium of the adult Amiurus by McMurrich 

 (1884), the skull of the Siluroids has been neglected. 



This study of Amiurus has been undertaken because of the low organiza- 

 tion of the Siluroids and the primitive relation of certain parts of the skull. 

 Many points of relationship with the ganoids have been found and a sounder 

 basis for grouping the Siluroids with the Characinidae and the Cyprinidae, 

 has been developed. Very early stages of the skull were not procurable, so 

 that the following account is based upon the 8, 10, 20, 32 and 60 mm. stages, 

 though earlier stages than the earliest of these may be described in a later 

 paper. Most of the material was obtained from Wisconsin, though the 32 mm. 

 stage was supplied by Professor J. S. Kingsley under whose direction the work 

 was completed, and whom I take this opportunity to thank for the many 

 helpful suggestions and facilities placed at my disposal. The adult specimens, 

 obtained through the generosity of the lUinois Natural History Survey, came 

 from the Illinois River. 



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