Type.—Adult female (skin and skull) No. 104683 U. S. National Museum. Collected on Pulo Laut, North Natuna Islands, August 6, 1900. Original number 612.
Characters.—Size slightly less than that of Sciurus rubidiventris and color conspicuously pallid. Upper parts as in S. lutescens; lower parts nearly as in S. seraiæ but rather less dull; pale side stripe much less yellow than belly. Skull as in Sciurus rubidiventris.
Color.—Upper parts and tail as in Sciurus lutescens. Cheeks faintly washed with ochraceous-buff. Under parts and inner surface of legs bright ochraceous-buff (distinctly more yellow than Ridgway's pl. V, No. 10). Lateral stripes as in S. lutescens (not distinctly yellowish as in S. seraiæ), but black band usually less sprinkled with gray. Scarcely a trace of gray in axillary region or on sides of neck.
Skull.—The skull in all respects closely resembles that of S. rubidiventris except that it is slightly smaller. Its large size and the correspondingly large teeth readily distinguish it from that of the South Natuna species.
Measurements.—External measurements of type: total length 375; head and body 195; tail vertebræ 180; hind foot 44 (41). Average and extremes of nine specimens from the type locality; total length 363 (355-379); head and body 189 (171-196); tail vertebræ 170 (165-183); hind foot 45 (44-46); hind foot without claws 42 (41-43).
Specimens examined.—Ten (one in alcohol), all from the type locality.
Remarks.—Though suggesting two of the small South Natuna squirrels in color, Sciurus lautensis is obviously related to the dark colored Bunguran form, with which it more nearly agrees in size.
SCIURUS NAVIGATOR (Bonhote).
1894. Sciurus prevostii Thomas and Hartert, Novitates Zoologicæ, I, p. 656. September, 1894 (Sirhassen).
1901. Sciurus prevostii navigator Bonhote, Ann. and Mag. Nat. Hist., 7th ser., VII, p. 171. February, 1901 (Sirhassen).