SCIURUS LUTESCENS sp. nov.
1894. Sciurus notatus Thomas and Hartert, Novitates Zoologicæ, I, p. 659. September, 1894 (part, specimens from Sirhassen).
Type.—Adult male (skin and skull) No. 104668 U. S. National Museum. Collected on Sirhassen Island, South Natunas, June 3, 1900. Original number 429.
Characters.—Allied to Sciurus notatus, but considerably smaller than the Bornean representative of the species. Colors very pale, the under parts buff or cream-buff (Ridgway, pl. v, nos. 13 and 11) irregularly tinged with gray.
Color.—Entire dorsal surface of body and tail a fine grizzle of black and cream-buff, the individual hairs black with two or three cream buff rings. On tail the grizzle is less fine than on back, and it shows a faint tendency to resolve itself into obscure cross bands. On sides of body and on head the cream-buff brightens to buff. Cheeks and muzzle buff, scarcely grizzled. Feet slightly yellower than sides, under parts and inner surface of legs pale buff, palest anteriorly and laterally (where it about matches the cream-buff of Ridgway) brightest along median line. Under side of tail dull ochraceous-buff slightly grizzled with black. Pencil not different from rest of tail. Between the colors of sides and belly are the usual longitudinal stripes. The outer of these is about 5 mm. in width, and cream-buff in color. The inner is about twice as wide, and black, but much obscured by a thick sprinkling of bluish gray hairs. Outer surface of ears concolor with neck, inner surface like cheeks. The sprinkling of bluish gray hairs on sides of belly extends irregularly forward to axilla and inner side of front leg, occasionally to throat and chin.
Skull.—As compared with the Bornean form of Sciurus notatus, the skull of S. lutescens is much smaller (greatest length about 45 instead of 50) the rostrum is relatively shorter and broader, and the audital bullæ are less elongate antero-posteriorly. Teeth as in Sciurus notatus except that they are uniformly smaller.
Measurements.—External measurements of type: total length 355; head and body 177; tail vertebræ, 177; hind foot 45 (41). Average and extremes of six specimens from the type locality: total length 356 (329-375); head and body 186 (177-196); tail vertebræ 170 (152-178); hind foot 43.8 (41-45); hind foot without claws 40.7 (39-42).
Cranial measurements of type: greatest length 45.4 (50.4)[19]; basal length 39 (43); basilar length 36.4 (41); palatal length 20 (23); palatal width between middle molars 6 (6); greatest length of nasals 13 (14.8); greatest width of both nasals together 6.6 (7); interorbital breadth 15.4 (17); mastoid breadth 21 (21); zygomatic breadth 26 (29); depth of braincase at anterior edge of basi-occipital 16 (16.8); mandible 28 (30); maxillary toothrow (alveoli) 8 (9); mandibular toothrow (alveoli) 8 (9).
Specimens examined.—Seven (one in alcohol), all from the type locality.
Remarks.—This squirrel is recognizable among the members of the S. notatus group by its light colors, and particularly by the pallor of the under parts. In the latter characteristic it is approached by the form inhabiting Pulo Laut, but with this exception it is unique among the fulvous bellied species. The six specimens show no variation worthy of note.