PAPERS ON ZOOLOGY 295 



quadrate, which has been called the maxillary process; 

 and the proximity of these two structures would suggest 

 an earlier continuity between them. Elsewhere in all 

 described Urodeles, the extent of the pterygoquadrate 

 forward from the quadrate is variable throughout the 

 order; and in the adult Cryptobranchus (and this holds 

 true for the Japanese japonicus, as figured by Parker, 

 1876) the connection between the pterygoid and the struc- 

 tures farther forward is lost. In the chondrocranium 

 of Epicrium glutinosum, the blind caecilian of the trop- 

 ics, the pterygoid process reaches well forward toward 

 the nasal region; and the proximity of the antorbital to 

 the pterygoid suggests that here, as in some of the Uro- 

 deles, these structures may have been at one time more 

 closely related. 



In all of the Anura, on the other hand, the pterygo- 

 quadrate arch is connected throughout life with the pos- 

 terior wall of the nasal capsule. In this respect, Rano- 

 don and Cryptobranchus more closely approach the 

 Anura than any other Urodele; for in the remainder of 

 the group, there is no connection of the pterygoquadrate 

 with the anterior part of the cranium. 



It is usual to regard the pterygoquadrate arch of the 

 Anura as the homologue of the upper jaw of the Elasmo- 

 branch, which, with the development of the osseous upper 

 jaw of the higher groups has lost its original function 

 as part of the feeding apparatus, and has fused with the 

 cranium, thus contributing toward the posterior wall of 

 the nasal capsule. In the chondrocranium of the Elas- 

 mobranch, there is no anterior extension of the pterygo- 

 quadrate beyond the curve of the upper jaw, to form any 

 integral part of the nasal capsule ; but in all of the Anura, 

 as far as I know, the side wall of the capsule is apparently 

 a continuation forward of the pterygoid, beyond its con- 

 nection with the cranium. In Pipa americana, a small 

 triangular cartilage plate, the ethmo-palatine of Parker, 

 continues forward from the pterygoid and partiallj^ cov- 

 vers the caudal parts of the nasal organ; while in Bufo 

 and Eana, the side wall of the capsule, better designated 



