tlie Species of ihe Genus Cavia. 153 



Cava guianc'^ Tlios. 



C. porceUus yuiance, Thos. Ann. & Mag. Nat. Hist. (7) viii. p. 152 

 (1901); 



and in Venezuela 



" Cavia por cell KS venezueicB," All. Bull. Am. Mus. xxx. p. 250 (1911), 



\vlin.se distinction from guiance appeav.s most douhtfnl. 



As regards guioue, the original statements about it^ 

 characters were largely influenced by the fact that at that 

 date the few available Brazilian specimens included both 

 aperea and what we now know to be the quite distinct 

 species /w/^iV/a. As a matter of fact, f^'a'ar/ce. has practically 

 the same colour as the real aperea, but is distinguished by 

 its smaller size, the largest of three full-grown shells only 

 measuring 63 mm. in length*, with length of buliaf 

 ]1"8 mm. and upper tooth-iow 14. The skull is pro- 

 portionately rather broadly built, with unusually develo[;ei 

 ])ostorbital projecting ledges. 



Specimens are in the British Museum from tlie Kanuku 

 Mountains, Berbice, and the Moon Mountains, all in Bi'iiisii 

 Guiana. 



Putting aside the Cavia porceUus of Linnteus, based on 

 the Cavia cobnya of Marcgrave, the domesticated <iuinea- 

 })ig, to which the name should be restricted, we next have 



Cavia aperea, Erxl. 



Cavia aperea, Erxl. Mamin. p. 348 (1777) (based on the ^^ Aperea*' of 



Marcgravej Bras. p. 223, 1048). 

 Ana-ma hilaria, Geoif. N. il. Mamm. (fol.) ii. text to pi. 282 (1820). 

 Cavia leucopyya, Brandt, Mem. Ac. Petersb. 183o, p. 436, pi. xvi. 



Size largest of the geiuis. General colour grizzled 

 brownish grey, not the clearer or more olivaceous grey of 

 the Ai'gentine forms. Below dull whitish or drabby whitish, 

 a clear white spot generally present on the middle line of the 

 chest just behiiul the brown collar. 



Tiie largest of the available skulls measures no less than 

 73 mm. in total length, while the average of half a dozen 

 from Minas Geraes and Sao Paulo is 68*7 mm. in total length, 

 bulla 11'9, tooth-row 15'5. The hind foot in adults varies 

 from 45 to 50 mm. 



* The skull-length is here always taken from the tip of the nasals, and 

 may sometimes be slightly exceeded by a slanting length from occipital 

 to gnathion. 



f Measured from the notch in front of the paroccipital process directly 

 forwards, parallel with the axis of the skull, not to the antero-internal 

 angle, ■which end(3 in an irregular point. 



