260 On a new Agouti from British Guiana. 



Dimensions of the type (measured on a well-made skin) : — 



Head and body 510 mm. ; hind foot 103 ; ear 40. 



Skull: greatest length 110; condylo-incisive length 95; 

 zygomatic breadtii 49; nasals 37*5 ; interorbital breadth 29'5 ; 

 palatilar length 42 ; upper tooth-series {p'^ in use and worn) 

 18-2. 



Hah. Moon Mountains, Southern British Guiana, about 

 1° N.j 59° W. Other specimens, apparently referable to the 

 same form, from the Lower liio Yamunda and from the 

 Upper Caura River, Orinoco. 



Ti/pe. Adult female. B.M. no. 11. 6. 7. 43. Original 

 number 9 a. Presented by the late Mr. F. V. McConnell. 

 Seven specimens. 



This subspecies differs from true D. aguti by the absence 

 of a mesial light stripe running down the chest and abdomen, 

 from croconota by the non-extension of the orange runjp- 

 colour on to the sides of the hips and down the legs, and from 

 the agouti of Nortiiern Britisli Guiana by its lighter general 

 colour, and especially its lighter fore back, without blackening 

 on nape and withers, and its less blackened feet. A baby 

 specimen, however, has both the darkened fore back and 

 blackish feet of the more northern form, which appears to 

 indicate either variability or change with age. But, as 

 Mr. McConnell's specimens were obtained by a native 

 collector, and the localities were sometimes misstated, it is 

 just possible that this young specimen was not from the 

 Moon Mountains at all, but came from Demerara, where 

 the same collector obtained a number of D. a. flavescens. 



In a recent paper Dr. Allen * rather unaccountably 

 (uidess he has been solely influenced by the reputed locality 

 "Guiana") considers that the Guianan yellow-rumped 

 agoutis should bear the name of D. croconota pjrymnolopha^ as 

 based on Wagler's D. prymnoloplia f ; but the latter is at 

 once distinguishable from all the aguti group by the black on 

 the centre of tlie rump, and it was no doubt quite erroneously 

 stated to be from Guiana, its true locality being Brazil — from 

 Para to Bahia. 



In this connection I may note that three agoutis from 

 Lamarao, Bahia, collected by A. Robert, clearly represent 

 Q^^QQ^^ D. nigriclunis\\ but they differ so widely among 



* Bull. Ann. Mus. xxxiv. p. 629 (1915). 



t 'Isis,' 1831, p. 619. 



\ Field Mus. Publ. x. p. 192 (1915). 



