SKELETON. 39 



(diapophyses), but these are present on the succeeding 

 eight vertebras, and in the Discoglossidse alone the 

 first three are segmented off into short autogenous 

 ribs. The transverse processes of the ninth vertebra 

 give attachment to the ilia, and are therefore termed 

 sacral ; their form differs much according to the 

 genera, — cylindrical in Rana, flattened and subtri- 

 angular in Discoglossus, Alytes, Bufo, and Hyla, or 

 very strongly dilated in Bombinator, Pelodytes, and 

 Pelobates. In the latter genus the sacral processes are 

 often yielded by the urostyle. The diapophyses ter- 

 minate in cartilaginous epiphyses. 



The urostyle, or coccyx, formed by coalescence of 

 at least two vertebrae, is a cylindrical solid rod with 

 more or less distinct dorsal crest, and articulates with 

 the sacral vertebra by two sockets, except in Bom- 

 binator, in which there is but one. In Pelobates the 

 urostyle is normally fused with the ninth vertebra, 

 and contributes to the sacrum ; in the Discoglossidse 

 a slender transverse process is present on each side 

 at the base of the urostyle. 



Abnormalities in the vertebral column are not un- 

 frequent, and many remarkable cases have been 

 described by Goette, Lataste, Camerano, Bourne, 

 Adolphi, and Howes. Thus two vertebras may fuse, 

 or the number of segments may be increased to eleven, 

 as in a vertebral column of Alytes obstetricans described 

 by Lataste ; in this interesting specimen the ninth 

 vertebra bears on the left side the dilated sacral dia- 

 pophysis, whilst the diapophysis of the opposite side 

 is slender and does not differ from that of the vertebra 

 in front of it ; the tenth vertebra, on the other hand, 

 bears a dilated diapophysis on the right side and a 

 cylindrical one on the left ; the urostyle is quite 

 normal, with the basal processes developed as usual. I 

 have also examined a skeleton of Bombinator pachy pus, 

 with eleven segments, all, including the sacral ver- 

 tebra and the urostyle, appearing perfectly normal in 

 shape. 



