THE BATRACHIA. OF NORTH AMERICA. 257 



edge indicates, finds its completest development in the extinct genus 

 'Latouia, established by Von Meyer on the L. seyfriedi from the Miocene 

 of Oeuiugeu, A species also occurs in the fresh-water deposits of San- 

 san {L. rugosa), whose salamander-like vertebrae have been noticed 

 by Gervais.* These animals, were nearly related to Discoglossus, and 

 had, like it, short posteriorly directed processes on the ribs, as in the 

 genus Salamandra. They were, however, much larger, had the fronto- 

 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. 



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 sternum, homologous with the sternum of 

 the Lacertilia, resembles the united hsema]3ophysial cartilages of the an- 

 terior ribs. In the genera in question t 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 Discoglossus the usual three 

 pairs of lineas semilunares, connected on the median line by a strong 

 Linea all)a. 



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 Hj^orhiua, Platyplectrum,. Limnomedusa, Pelody- 

 tidie and the ScaphiopidcTB. A species {A. tro8clielii)X has left its re- 

 mains in the Miocene Braunkohle along with Palteobatrachus. Bom- 

 binator is similar to Alytes in its osseous structure, except that the 

 prefrontalia are in contact anteriorly only, and that the sacrum pre- 

 sents but one condyle for the articulation of the coccyx, as is typical 

 of the Asterophrydidte and Aglossa. Along with Alytes and Xen- 

 opus it has true ossa nasalia, which bound the external nares exte- 

 riorl}^ thus explaining their anomalous position in Breviceps, where 

 they are inferior. In Bombiuator there is no cavum tympani or auricu- 

 lar ossicles, and the tubse Bustachii are rudimentary or wanting. This 

 character is said by Tschudi and Bruch not to be exceptionless in 

 adults, and that the tubae and tympanum are always present in the 

 young of both this genus and Pelobates. All European, except Lio- 



* PalsBontologie Frangaise, p. 494. 



\ Du_i;es lias given a figure of it in Bomhinator, PI. 3, fig. 24. 



+ Cope, Joiu'ii. Acarl. Phila., 186G, p. 75. liana troschelii (Von Meyer, Palaeoutograpb- 

 iea, III, p. 138). 



1951 —Bull. 34 11 



