1915.| Allen, Review of the South American Sciuride. 197 
very little developed. Their surface more smoothly basin-shaped, with 
less evident transverse ridges.” 
“As a genus, Sciurillus is very closely related to Nannosciurus, the 
reduction in the prominent transverse ridges of its molars, the peculiar 
structure of its anteorbital foramina, and its high but abruptly truncated 
ectopterygoids being its chief distinguishing characters. From Myosciurus, 
though both are undoubtedly of the same group, it is more widely sepa- 
rated”’ (Thomas, l. c.). 
Sciurus pusillus, the Guiana pigmy squirrel, although well described 
and figured by Buffon in 1798, and first technically named from Buffon’s 
specimen by Desmarest in 1817, has always been poorly represented in col- 
lections, and consequently very imperfectly known. ‘Thomas first described 
its cranial characters in June, 1914, from the study of “a practically perfect 
skull,” then recently received at the British Museum. “An examination 
of this skull,” he says, “shows that instead of being in any way related to 
Microsciurus [to which genus it has of late years been referred] or other 
forms of American Sciurine, the Guianan Squirrel is a member of the 
Nannosciurine, in which it forms a special genus closely related to Nanno- 
sciurus.’ As the Nannosciurine have heretofore been supposed to be 
“rigidly restricted to a small part of West Africa and to the Malay Archi- 
pelago,” he adds: “The addition of Guiana to the known distribution ot 
the group is therefore of extraordinary interest.” 
Sciurillus pusillus pusillus ( Desmarest). 
Le petit guerlinguet Burron, Hist. nat., Suppl., VII, 1789, p. 263, pl. Ixvi 
(Cayenne). 
Scliurus] pusillus DEsMAREST (ex Geoffroy MS.), Nouv. Dict. d’Hist. nat. (nouv. 
éd.), X, 1817, p. 109 (based on Buffon, as above). 
Macrozus pusillus Gray, Ann. and Mag. Nat. Hist. (3), XX, p. 433, Dec. 1867 
(Guiana). 
Sciurus pusillus Auston, Proc. Zool. Soc. London, 1878, p. 670, pl. xli, part.— 
ALLEN, Bull. U. S. Geol. Survey (Hayden), IV, No. 4, pp. 887, 905, Dec. 11, 1878, part. 
Microsciurus pusillus AuuEN, Bull. Amer. Mus. Nat. Hist... XXX, yp. 154, 
Feb. 26, 1914 (general account). 
Macrozus kuhlit Gray, Ann. and Mag. Nat. Hist. (8), XX, p. 443, Dec. 1867, 
“Brazil” (= probably Guiana). 
S{ciurus| kuhlit (Gray) Neuson, Proc. Washington Acad. Sci., I, p. 32, May 9, 
1899 (in text). Referred to Microsciurus. 
Miscrosciurus kuhlii ALLEN, Bull. Amer. Mus. Nat. Hist., XX XIII, p. 162, Feb. 
26, 1914 (description from Gray, and comment). 
Type locality.— Cayenne. 7 
Geographic distribution.— Cayenne (Buffon); Guiana (Gray). 
