1915.] Allen, Review of the South American Sciuride. 205 
deep yellow, a little lighter on throat and chin than on the belly; tail above, 
at the extreme base, like the back, rest of the upper surface blackish, the 
hairs with long reddish yellow tips often nearly concealing the darker basal 
portions; under surface of tail grizzled orange and black medially, with a 
broad subterminal band of black strongly edged outwardly with reddish 
yellow or orange; ears reddish yellow with bright orange postauricular 
patches; upper surface of feet finely grizzled orange and black, the toes in 
some specimens becoming clear orange yellow, in others not different from 
the proximal portion of the foot. 
Ten adult specimens (7 females, 3 males), from Astillero, San Carlos, 
San Ernesto, Yungas, and Charumplaya, Bolivia (long. 65°-68°, lat. 15°- 
16°), collected and measured by P. O. Simons: Total length, 355 (342- 
370); head and body, 180 (160-198); tail vertebrae, 178 (160-180); hind 
foot (s. u.). 46.6 (45.48). (See also Table II, p. 208.) 
Specimens examined, 13.— Bolivia: Astillero, 3 (type and 2 topotypes); 
‘Charumplaya, 2; San Carlos, 2; San Ernesto, 3; Yungas, 3 (all in Br. Mus., 
except 1 of the Yungas specimens, which is in Am. Mus.). 
Remarks.— Sciurus cuscinus ochrescens has been described since my 
examination of the “cuscinus’’ material in the British Museum. At that 
time I was strongly impressed with the wide range of color variation shown 
in series of specimens from the same locality, and was rather surprised when 
I received the description of “ ochrescens’’, based on the Bolivian specimens. 
It being impracticable for me to reéxamine the cuscinus group material, I 
provisionally accept ochrescens (=ignitus), moved partly to-this decision by 
Thomas’s opinion and partly by the geographical probabilities of the case. 
The “ cuscinus’’ group, as now known, occupies an oval area of considerable 
geographical extent in the Peru-Bolivia Andes, with its major axis running 
in a northwest-southeast direction, from west longitude 65° at the south to 
72° at the north (approximately 500 miles), and between 12° and 16° south 
latitude (approximately 300 miles). The type localities of cuscomus and 
ochrescens are, respectively, as are those of irroratus and ignitus, at the 
extreme northwestern and extreme southeastern borders of this area, and 
therefore widely separated in a region of considerable physiographic diver- 
sity, yet the two forms are only slightly differentiated. 
In this connection two questions of nomenclature require consideration. 
In 1867, Gray described two species that evidently belong to the ““cuscinus”’ 
group, both from localities not definitely indicated, namely, Macroxus wrro- 
ratus, from Peru, collected by E. Bartlett on the “Upper Ucayali”; and 
Macroxus ignitus, from “Bolivia (Brydges),” probably on the Upper Rio 
Beni. M. ignitus precedes by two pages the name irroratus, both names 
