7] THE NA SA L ORGA N IN A MPHIBIA BIGGINS 



INTRODUCTION 



There is considerable literature upon the development of the chondro- 

 cranium of the Amphibia, but only a little of it gives adequate details of the 

 process of chondrification of the nasal capsule in fchis class of vertebrates. 



Parker, in a long series of extensively illustrated papers, (1871, 1876, 

 1877, 1881) was the first to give any adequate account of the development 

 of the skull in the Amphibia; but his remarks, so far as the nasal capsules 

 are concerned, are general and no detailed description of the parts or pro- 

 cesses of chondrification are given. Born (1877) gives, in considerable 

 detail, the process of chondrification in Triton cristatus; while Stohr (1879) 

 who also described the chondrocranium of Triton, paid but slight attention 

 to the ethmoidal region. 



Gaupp (1893) in his well known work on the cranium of Rana fusca 

 discusses four stages in the development of the skull of the frog, treating all 

 parts with more detail than any other writer. According to Miss Platt 

 (1897) the nasal capsule in Necturus, to a great extent, chondrifies inde- 

 pendently of the trabeculae; but she gives but slight account of the develop- 

 ment of the fenestrated roof of the capsules. Winslow (1898) dealt with 

 the chondrocranium of several of the Ichthyopsida, but his account of the 

 development of the nasal capsules has but slight detail. Peter (1898) is 

 the only one who has described the skull of any Gymnophione; while 

 Terry (1906), who followed the history of the nasal capsule of Amblystoma 

 through five stages, states that the process of chondrification in Amblys- 

 toma agrees closely with that of Triton. 



The work covered by this paper was undertaken with the idea of ascer- 

 taining what homologies, if any, could be drawn between the nasal capsules 

 of the various groups of Amphibia; and to determine in how far these 

 structures would substantiate or alter the different classifications proposed 

 for this vertebrate group. 



The work was done in the Zoological laboratory of the University of 

 Illinois, almost entirely upon the departmental collection. It was carried 

 on under the supervision of Professor J. S. Kingsley to whom the writer 

 wishes to acknowledge his sincere appreciation for the many helpful sug- 

 gestions and his kindly attitude during the investigation and the prepara- 

 tion of this paper. I wish to acknowledge my best thanks to Professor 

 A. C. Eyclesheimer of the University of Illinois College of Medicine, for the 

 loan of several of his series of slides of Necturus. 



