7) THE NASAL ORGAN IN AMPHIBIA—HIGGINS 7 
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 this 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 Stéhr (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. 
