On the Osteology of the Genus Platysternum. 461 



other transitional forms (e. g. Hemitragus jemlaicus) were 

 derived the modern goats. Capra caucasica is quite a typical 

 goat, having a close affinity with the Swiss species [Capra 

 ■ibex, L.) and inhabits the Western Caucasus. Lastly, the 

 goat with_ short thick horns inhabiting tlie westernmost parts 

 may possibly form a fourth distinct species. 



The horns oi ^goceros Fallasii figured in the accompaning 

 Plate (lig. 2) are taken from a very good skull preserved at the 

 museum of the Academy of Sciences. Those of Capra caucasica 

 (fig. 1), from photographs taken by me, represent two forms 

 — one a short-horned and the other a long-horned specimen. 



LXI. — Notes on the Osteology of the Oenus Platysternum. 

 By G. A. BOULENGER. 



[Plates XVI. & XVII.] 



The genus Platysternum, Gray, contains but one species, P. 

 megacephalum, Gray, inhabiting Southern China, Siam, and 

 Burma. Young specimens have been described by Gray as 

 a distinct species, P. peguense. With the object of ascertain- 

 ing the correct systematic position of this curious genus, of 

 which the external characters only were known, I have had 

 prepared a skeleton from a half-grown specimen (shell 10 

 centim. long), obtained in Southern China by J. Reeves. I 

 have also been able to verify some points on an adult example, 

 in spirit, from Laos, parts of wliich have recently been cut 

 away by Professor Huxley with the object of examining the 

 skull and the caudal vertebrae. 



Carapace. — Although the specimen is only half-grown, the 

 ossification of the carapace is perfect, with the only exception 

 that the sutures between costal plates 2 to 4 and the corre- 

 sponding marginals have not yet completely joined. It con- 

 sists of a nuchal, eight neurals, eight costals, three pygals, 

 and twenty-two marginals. The nuchal is nearly twice as 

 broad as long, without costiform processes, its outline the same 

 above and below. The first neural is slightly longer than 

 broad, the second to seventh are subequal and broader than 

 long, the eighth is very small and thrice as broad as long. 

 The seventh pair of costals are in contact witii the seventh 

 and eighth neurals and the anterior pygal. The latter plate 

 is trapezoid, much broader than long, a little longer and a 

 little narrower than the second pygal, which forms likewise a 

 Ann. & Mag, N. Hist. Ser. 5. Vol. xix. 32 



