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 breadth 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., 59° W. Other specimens, apparently referable to the 
same form, from the Lower Rio Yamunda and from the 
Upper Caura River, Orinoco. 
Type. Adult female. B.M. no. 11.6. 7.48. Original 
number 9a. Presented by the late Mr. F. V. McConnell. 
Seven specimens. 
This subspecies differs from true D. agutt by the absence 
of a mesial light stripe running down the chest and abdomen, 
from croconota by the non-extension of the orange rump- 
colour on to the sides of the hips and down the legs, and from 
the agouti of Northern British 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 
(unless he has been solely influenced by the reputed locality 
“ Guiana”) considers that the Guianan yellow-rumped 
agoutis should bear the name of D. eroconota prymnolopha, as 
based on Wagler’s D. prymnolophaf; but the latter is at 
once distinguishable from all the aguti group by the black on 
the centre of the 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 
Osgood’s D. nigriclunis}; but they differ so widely among 
* Bull. Ann. Mus, xxiv. p. 629 (1915). 
+ ‘Isis,’ 1831, p. 619. 
t Field Mus. Publ. x. p. 192 (1915). 
