1871.] MR. P. L. SCLATER ON ANIMALS IN THE MENAGERIE. 747 



of difference in the skulls of the two species, to which Mr. Bartlett 

 has called my attention. In P. dmmeriliana there is a large oval 

 fossa (a/, fig. 2), about two tenths of an inch in depth, immediately 

 in front of the aperture (ac.) in which the columella is lodged. 

 This fossa does not exist in the skull of P. expansa (fig. 1 ), or at 

 least is only shown by a slight depression of the surface in the same 

 spot. Moreover the large somewhat triangular-shaped fossa be- 

 hind the aperture (pf), which occurs in both species, is very much 

 larger in P. dumeriliana than in P. expansa. 



Fig. 1. 



Fig. 2. 



ac 



Right tympanic rings of Podocnemis expansa (fig. 1) and P. dumeriliana (fig. 2). 

 pf. Posterior fossa, af. Anterior fossa, ac. Aperture of the columella. 



3. The Tortoise recently named by Dr. Gray Bartlettia pitipii* , 

 which Mr Bartlett met with only near Sarayacu, on the Ucayali'. 

 This, he states, *' lays from nine to twelve eggs only, on the flat sand- 

 banks, about fifty or sixty yards from the water." The eg»s, of 

 which I exhibit two specimens from Mr. Bartlett's collection, are 

 oblongo-oval in shape and soft-shelled, measuring 17 by 0*9 inch. 



There is no question about this Tortoise being a Podocnemis, in 

 my opinion, and probably of a species different from P. expansa and 

 P. dumeriliana. But I consider that it may be referable to Emys 

 erythrocephala of Spix, with which it agrees in nearly every parti- 

 cular. In the first place Spix's species is unquestionably a Podo- 

 cnemis, but has been referred by some authors to P. dumeriliana 

 and by others to P. expansa, both of which species Spix has figured 

 under other names. Wagler, who had the advantage of the use of 

 Spix's specimens, says (Nat. Syst. d. Amph. p. 13.5) "Emys ery- 

 throcephala, Spix, which belongs to this genus (i. e. Podocnemis) 

 differs from Emys expansa only in the circular excavation at the end 

 of the thorax by the tail. Perhaps this is only individual." The 

 complete specimen of the so-called Bartlettia pitipii in the British 

 Museum, as will be seen by the accompanying sketch (fig. 3, p. 748), 

 presents this feature to a certain extent, although not to the extent 

 given in Spix's figure. 



* P. Z. S. 1870. p. 720. 



