GENERA OF THE ARCIFEROUS ANURA. 75 



exteriorly diverging fibro-cartilaginous or cartilaginous styles. Tongue round, 

 entire, and little or not at all free behind. Males without vocal vesicle. 



If we commence the series of the Arcifera with the great family of the Cystigna- 

 thidag, we will end it with the families Asterophrydida? and Discoglossidse, which are 

 perhaps equally connected with that which precedes them — the Scaphiopodida^. The 

 former leads to Dactylethra through Palfeobatrachus ; the latter, as far as our 

 present knowledge indicates, finds its completest development in tbe extinct genus 

 Latonia, established by Von Meyer on the L. s e y f r i e d i from the miocene of 

 Oeningen. A species also occurs in the freshwater deposits of Sansan, L. r u gosa, 

 whose salamander-like vertebras have been noticed by Gervais.* These animals 

 were nearly related to Discoglossus, and had, like it, short posteriorly-directed pro- 

 cesses on the ribs, as in the genus Salamandra ; they were, however, much larger, 

 had the fron to-parietal bones completely ossified, and the whole of the cranium 

 roughened externally by a dermo-ossification. On this account the genus has been 

 compared with Ceratophrys, which belongs to the family of Cystignathidse. This 

 dermo-ossification occurs in various families, especially in the New World. 



In the remaining and recent genera, the structure of the sternum is worthy of note. 

 In old individuals of Discoglossus, it is sometimes fibro-cartilaginous, as in Pipa. 

 The xiphisternum, proximally homologous with the xiphisternum of the Lacertilia, 

 consists distally of the united hsemapophysial cartilages of the anterior ribs. In 

 the genera in question,! this part is divided nearly up to the point of attachment to 

 that preceding, each moiety being directed outwards and backwards, and tapering 

 into a lateral linea semilunaris. Between these and the pubes there are in Discoglos- 

 sus the usual three pairs of linese semilunares, connected on the median line by a 

 strong linea alba. 



In Discoglossus the prefrontalia are strongly developed, being in contact for most 

 of their length, sometimes touching the fronto-parietalia. In Alytes they are also in 

 contact throughout, but are transverse and do not reach the fronto-parietals ; the 

 fontanelle is larger, and the ribs without processes : the whole animal is weaker. In 

 this genus, as well as the preceding, the pupil is a vertical slit ; elsewhere found 

 in Hylorhina, Platyplectrum, Limnomedusa, Pelodytidse and the Scaphiopodidaj. A 

 species, A. t r o s c h e 1 i i ,J has left its remains in the miocene Braunkohle along 

 with Pal^obatrachus. Bombinator is similar to Alytes in its osseous structure, 

 except that the prefrontalia are in contact anteriorly only, and that the sacrum 

 presents but one condyle for the articulation of the coccyx, as is typical of the Aste- 

 rophrydidaj and Aglossa. Along with Alytes and Dactylethra it has true ossa 



* Palaeontologie Prancaise, p 494. 



t Duges has given a figure of it in Bombinator. pi. 3, fig. 24. 



t Rana troschelii (Von Meyer, Palseontographica, iii. p. 138) is undoubtedly an Alyles. 



