c/ 



THE HYO-BRANCHIAL APPARATUS OF TYPHLO- 

 TRITON SPEL^US STEJN. 



WILLIAM A. HILTON, PH.D. 



The cave salamander Typhlotriton was put in the family 

 Desmognathidse by Stejneger, in 1892. l The basis of this classi- 

 fication was chiefly certain skeletal characters, such as the struc- 

 ture of the vertebrae. The study of the hyo-branchial apparatus 

 of this form seems to show other relationships. 



In the larvae of Typhlotriton, which are often found almost 



FIG. i. Hyo-branchial apparatus of full grown larva of Typhlotriton 

 spel&us from above, showing three branchial bars and a three-pointed " Copu- 

 lastiel." X 6. 



as large as the adult, only three branchial arches are found. Fig. 

 i, instead of four which are found in the larvae of other members 

 of the family Desmognathidae, Fig. 2. 



In the adult Typhlotriton, the general character of the hyo- 

 branchial apparatus is much like the type found commonly in the 



1 Stejneger, Leonhard, " Preliminary Description of a New Genus and 

 Species of Blind Cave Salamander from North America, Proc. U. S. Nat. 

 Museum, Vol. XV., 1892. 



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