the Species of tJie Genus Cavia. 159 



This remarkable little cavy furnishes a good example of 

 the difficulty of distinguishing young specimens from old 

 in this group ; for^ in spite of the fairly close survey of the 

 collection always kept up, no one has previously noted that 

 Mr. Pentland's specimen, received sixty-six years ago, is 

 fully adult, and it is only on the general examination of the 

 group now made that I have found this out, and am able to 

 give Mr. Pentland the credit for a very interesting discovery. 

 The first scientific exploier of the Titicaca plateau, he sent 

 home quite a number of interesting specimens, but, of course, 

 had not been instructed as to the proper preservation of data. 

 On this account I have chosen one ol Mr. Simons's three 

 specimens as the type. These were erroneously called 

 C aperea in my account of the latter's Bolivian collection. 



In proof that the specimens are full grown, I may note 

 that the type has its basilar suture closed, while Mr. Pent- 

 land's specimen has already the tell-tale sagittal crest charac- 

 teristic of old individuals. 



Lastly, we have the Brazilian species with the deep notch 

 on the outer side of vi^ already referred to. Tiiere appears 

 to be only one species of this group, whose name and 

 characters are as follows : — 



Cavia fulyida, Wagler. 



Caviafulgida, Wagler, Isis, xxiv. p. 512 (1831) ; Wagn., Schr. Saug., 



Supp. iv. p. 59 (1643) (redesciiption of type). 

 Cavia 7-iifescens, Lund, K. Dansk. Vid. Selsk. viii. p. 282 (1841). 

 Cavia niyricans' aii(\. " Kerodo}i obscurus, Licht.," Wagu., Schr. Saug., 



Supp. iv. p. 64 (1843). 



Size comparatively small, greatest skull-length rarely 

 attaining 60 mm. Colour rich dark grizzled brown ; under 

 surface deep buffy or ochraceouf', dulled by the greyish 

 bases of the hairs showing through to a variable extent. 



Last upper molar with a deep indentation on its outer side 

 at the anterior end of the posterior lobe. 



Range from Lagoa Santa, Minas Geraes, to Santa Calhe- 

 rina ; type said to have been obtained on the "Amazonian" 

 journey of Spix *, but the species is not known to occur on 

 the Amazon. 



* Spix's other explorations were mostly in the region inhabited by the 

 species I now call C. fulgida, and some error probably crept in as to the 

 particular trip on which it was collected. Or, with the loose geography 

 of the time, all his Brazilian journeyings may have been spoken of as 

 •' Amazonian." Wagner expressed certainty as to the identity oi fulgida 

 and 7-ufescens, and there appeal's to me no doubt about it. 



