326 



L OWER VER TERRA TES. 



pouch secrete the necessary additional quantit}- to supjily all that is required for 

 development. In so far as observation has extended, this is a solitary instance among 

 Batrachians, in which the embryo is nourished at the expense of the materials derived 

 from the parent." 



The family Xenopodid^ agrees with the Pipidw in all important respects, as the 

 structure of the skull, the scapular arch, coossification of sacrum and coccyx, etc. (Fig. 

 192), but differs in the jn-esence of teeth in the upper jaw. It includes but the single 

 genus ^enopus, which is represented by three species of the Ethiopian realm. Its toes 

 are acute, and the feet are broadly webbed for aquatic life. There is a short tentacle 

 below the eye. This is a remnant of the balancer, which characterizes the larvoe. 

 These creatures have, on each side of the head, a long tentacle extending backwards, 

 giving them very much the appearance of a siluroid or cat-fish. The species are of 

 plain colors. 



Sub-Order II. — Arcifera. 



The Anura of this division fall into nine families, which differ in simple and gener- 

 ally obvious characters. Thus the Bufonidie and Dendrophryniscida; have no 

 teeth whatever, and the former family, which includes the true toads, differs from the 



Fig. 194. — Skeleton of Ccratophrys ilorsata. 



latter in having the transverse processes of the sacrum much expanded and flattened 

 (Fig. 192), as distinguished from the subcylindric form seen in the Dendrophryniscidte. 

 This difference separates several other families also. Five of the remaining families 

 have teeth in the upper jaw only. In one of these, the Cystignathidje, the sacral transverse 

 processes are cylindric. Fig. 194, and in the four others they are expanded. Two of 

 these differ much from the other two in having the ball and socket of its vertebrae 

 related in a way the revei-se of what is seen in all other members of the order, but 

 similar to the structure found in many of the salamanders. That is, the ball is in 



