276 Bulletin American Museum of Natural History. [Vol. XXXIV, 
Sciurus pyrrhonotus and Sciurus igniventris are apparently representa- 
tive forms of the same species, for which the name zgniventris has priority 
of place on the same page. In size and in pattern of coloration there is a 
close similarity, the differences being the different shades of color that make 
up the different areas of the pattern. The rostral part of the skull, however, 
is much narrower in pyrrhonotus than in igniventris, with much narrower 
and shorter nasals. 
Urosciurus pyrrhonotus castus ( Thomas). 
Sciurus pyrrhonotus Tuomas, Ann. and Mag. Nat. Hist. (7), VI, p. 139, July, 
1900, part (Yungas and Missiones, upper Marmoré, Bolivia). 
Sciurus castus Tuomas, Ann. and Mag. Nat. Hist. (7), XI, p. 488, May, 1903. 
Type locality.— Chimate (altitude 700 m.), Bolivia, long. 68° W., lat. 
15° S., on the upper Rio Bene. 
Geographical distributton— Known only from the Department of 
Yungas, upper Rio Bene, Bolivia. 
Description.— Similar to Sciurus pyrrhonotus, but ventral surface and 
inside of limbs “pure sharply defined white.” 
Specumens examined, 1.— “Brazil,” 1 (Field Mus.). 
Remarks.— A specimen in the Field Museum of Natural History (No. 
8283), from “Brazil” (bought of E. Gerrard), agrees well with the descrip- 
tion of castus, except that the ventral surface and inside of the limbs, throat, 
chest, and greater part of abdomen (especially medially) are clear white, 
but the pelage is very thin, the skin showing through the hairs; the sides of 
abdomen posteriorly and the inside of the hind limbs are pale yellow. The 
basal third of the tail is mixed rufous and blackish, in general effect a little 
darker than in true pyrrhonotus. 
Urosciurus langsdorffii langsdorffii (Brandt). 
Plate XI, Figs. 4-6. 
Sciurus langsdorfii Branpt, Mém. Acad. Sci. St. Pétersbourg (6), Math. Phys. 
et Nat., III, pt. 2, 1835, p. 425, pl. xi, animal and skull (“Brasilia’’)— WaGnur, 
Suppl. Schreber’s Sauget., III, 1843, p. 183; Abhandl. K.-B. Akad. Wissen. Miinchen, 
V, 1850, p. 273, Cuyabd, Matto Grosso, Brazil.— THomas, Proce. Zool. Soc. London, 
1903 (April 1, 1904), p. 237 (Chapada, Matto Grosso, Brazil). 
Sciurus variabilis ALLEN, Mon. N. Amer. Rodentia, 187 7, p. 768, part; Bull. U.S. 
Geol. and Geogr. Survey Terr. (Hayden), IV, No. 2, p. 884, part. (The status of S. 
langsdorffit discussed on pp. 769, 770).— Atston, Proc. Zool. Soc. London, 1878, 
p. 665, part. 
