22 



ANURA 



CHAP. 



as in the Tkaiiidao and Cystignathidae, or they are more or less 

 tlilated as in all the other families, most strongly in the 

 Pelobatidae and the Aglossa. In some members of the large 

 sub -family of the Cystignathidae the otherwise cylindrical 

 diapophyses are slightly dilated. 



The sacrum is formed Ijv the ninth vertebra, but there are 

 a few interesting exceptions. Pdohates, Pipa, and Hymenochirus 

 possess two sacral vertebrae ; and, neglecting individual abnor- 

 malities, these three genera form the only exception amongst 

 recent Amphibia. In the three genera the coccyx is fused with 

 the second sacral vertebra, and such a fusion occurs elsewhere 

 normally only in Bombinator with its single sacral vertebra. 

 The morphologically oldest condition is normally represented by 

 Pdohates, the sacral vertebrae being the tenth and ninth. One 



Fit;. 4. — Dorsal view of tlie .sacral or uiutli vertebra (9), with tlie attachment of tlie ilimii, 

 of (1) Ranu teinponiria, (2) Jii'/o vi(/garis, showing the whole coccyx and pelvis, (3) 

 I'elobates J'usciis, as examples of cylindrical and of dilated sacral diapophyses. 

 (Aliout nat. size.) a. Acetabulum ; r, coccy.v ; /, ilium ; ,v, anterior zygapophyses. 



case has been recorded Ity Boulenger of Bomhiudfor jnn'Jri/pvs 

 " with eleven segments," the last carrying the ilium. Individual 

 lop-sided abnormalities have been described in Bomhinafor and 

 Alytes, where the right ilium articulated with the tenth, the left 

 ilium with the iiintli vertebra. This shifting forwards of the 

 ilium to the extent of one metamere has been continued furtlier 

 in I*ipa, in wliicli the sacrum is formed by the ninth and eighth 

 N'ertebrae, their diapophyses fusing on either side into extra broad 

 wing-like expansions. In old specimens o? Palaeohafrnr/ivs/rifschi 

 tlie seventh vertelaa is in a transitional condition, tlie ilium 

 l)eing carried by the ninth and t'ighth, and slinhlJy also by the 

 diapo]ihyses of the seventh vertebra; and in /'. i/i/i/riatu's the 



