the Species of the Genus Civia. 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 explorer of the Titicaca plateau, he sent 

 liome 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 o£ 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 Brazilinn species with the deep notcli 

 on the outer side of nfi already referred to. There appears 

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

 characters are as follows : — 



Cavia fulgida, Wagler. 



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



Supp. iv. p. 59 (164r3) (redescription of type). 

 Cavia riifescens, Lund, K. Dansk. Vid, Selsk. viii. p. 282 (1841). 

 Cavia niyricans and " Kerodon 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 ochraceous, dulled by the greyish 

 bases of the iiairs 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. 



Eange from Lagoa Santa, Minas Geraes, to Santa Cathe- 

 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 fidgida 

 and rnfescens, and there appears to me no doubt about it. 



