760 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
although in size and coloration it agrees perfectly with the descriptions of 
S. pusillus.* 
The next synonym of the Brazilian Squirrel (var. e@stuans) is the S. gil- 
vigularis (Natterer, MS.), a species first described by Wagner in 1843, based 
on specimens from the mouth of the Rio Madeira, having the chin and throat 
ochre-yellow. This form he regarded as the northern representative of the 
S. @stuans of Southern Brazil. In 1863, Peters gave the varietal name 
guianensis to specimens from British Guiana, also immature, though much 
larger than the S. pusid/us of Geoffroy. Two of the numerous nominal species 
described by Dr. Gray, namely, S. flaviventer and S. kuhlic from “Brazil”, 
are also undoubtedly referable to var. @stuans, as is also his MW. leucogaster 
from Eastern Bolivia. 
The first name applicable to the northern form of Sciurus estuans seems 
to be the rufoniger of Pucheran, given in 1845 to specimens from Santa Fé de 
Bogoté. In the same article, the name chrysurus was given to other speci- 
mens from the same locality. The first name was applied to examples having 
the middle of the body dark, the sides reddish, the chin and throat gray, and 
the tail ringed with red and black; the second to specimens with the dorsal 
surface uniformly colored, the throat yellow, and the tail washed with golden. 
To the extreme phase of this species, as developed in Costa Rica, Peters, in 
1864, applied the varietal name hoffinanni (Sciurus estuans var. hoffmanni), 
in which the size is rather larger and the colors stronger, especially the rufous, 
than in the New Granada specimens. Gray’s Sciurus hyporrhodus, described 
in 1867, was based also on specimens from Santa Fé de Bogota, apparently in 
full winter pelage, which are unquestionably referable to the form previously 
named by Pucheran. His description applies in every detail to numerous 
specimens before me from Costa Rica. Gray’s Macroxus irroratus, from the 
Upper Ucayali, Eastern Peru, also belongs here, showing that this rufous 
form of Sciurus @stuans ranges quite far southward along the eastern base 
of the Andes. I also refer to this form the same author's M. griseogena from 
Mexico, Honduras, Costa Rica, Panama, and Santa Fé de Bogota. 
GEOGRAPHICAL DISTRIBUTION.—Sciurus @stuans, including its two varie- 
*Butfon’s description of Le Petit Guerlinguet would lead one to suppose it to have been based on an 
adult individual. Hesays.... ‘‘les testicules de ce petit guerlinguet étoient beaucoup plus gros que 
ceux du grand guerlinguet, & proportion du corps, quoique ces partes présent dans le grand guerlinguet 
de la méme grosseur que dans nos écureuils.” —( Hist. Nat. Suppl. tom. vii, p. 264.) It seems certain that a 
species of Squirrel so remarkable as this could not so long remain unknown in a region whose zodlogy 
is now so well known as that of Cayenne and Eastern Brazil. 
