254 BULLETIN 34, UNITED STATES NATIONAL MUSEUM. 



agree with the bulk of tbe tribe in possessing dilated sacral diapophy- 

 ses, whilst those at the other extreme exhibit them cylindrical. (3) A 

 few of the former j)ossess small ribs, and (4) the urostyle approaches 

 tbe normal condition of vertebrae in possessing one pair of trans- 

 verse processes ; (5) uiost of these, with the adjoining less extreme 

 forms, have a vertical or cat-like pupil. (0) Many of the same group 

 exhibit a degraded or obliterated auditory apparatus ; but this feature 

 is not uniformly coincident with tbe preceding ones. (7) The xijjhi- 

 sternum is formed of divergent limbs ; in the bulk of tlie tribe it is an 

 emarginate cartilaginous plate, and in the opposite extreme an osseous 

 style, as in tbe Eanidaj. 



Of these features tbe first, third, fourth, and sixth are agreements 

 with or approximations to the structures of the same elements ol" the 

 Salamanders; the resemblances are borne out in the physiology of the 

 same types. 



In the observed examples of the above types that is, of tbe Disco- 

 glossidie, Pelod^^tidiC, and Scapbiopodidie, the eggs are deposited in 

 small clusters (Pelodytes), a short thick loop (Pelobates), or in a series 

 with a slender, tough, thread-like attachment (Alytes). In the family 

 following that of tbe Pelobates, that is the New World tree-toads, the 

 eggs are, in the Old World '■species {Hyla arborea) deposited in globu- 

 lar masses, as among the Eanidte, but much smaller, while, in our 

 Eyla piclceringii the masses include but from four to ten eggs. In the 

 first-mentioned forms the male seizes tbe female in front of the thighs, 

 while in the remaining and major number of species, as well as in the 

 observed Firmisternia, she is seized around the axillte. 



Additional peculiarities in the development of Alytes, Pelodytes, 

 Cultripes, and Pelobates are, that they spawn at two seasons instead 

 of one, and that their larv?e attain a larger size than those of other 

 Anura before completing their metamorphosis. This latter feature is, 

 however, repeated near the other end of the series — anaong those with 

 cylindrical i)elvic supports, in tbe genus Pseudis. 



The occurrence of a xiphisternal style similar to that of tbe Rauidai may 

 be regarded as an indication of superiority not only in consideration 

 of this affinity, but as a greater degree of specialization and ossifica- 

 tion of the part. It appears, however, not merely among tbe most 

 raniform Arcifera, and among some with proccelous vertebrae, which 

 have the salamander-like mode of reproduction, but also among some 

 of the opistbocoelous species. 



The only family features as above given which seem to have a func- 

 tional significance, are the- structure of the terminal phalanges as an 

 adaptation to arboreal life in tbe HylidiE and the increase of raptorial 

 power by the addition of another set of teeth in the Hemipbractidas. 

 Yet for tbe first-mentioned function other arrangements are employed 

 in other families. 



