braincase at anterior edge of basi-occipital 17.8 (16.8); mandible 29 (30); maxillary toothrow (alveoli) 9 (9); mandibular toothrow (alveoli) 9 (9).

Specimens examined.—Seven, all from the type locality.

Remarks.—In both size and general color this squirrel more closely resembles the Bornean representative of the group than it does either of the three forms from the South Natunas. Its relationships, however, appear to be rather with the race inhabiting Singapore Island than with any of its near geographic allies, Sciurus lautensis excepted.

SCIURUS LAUTENSIS sp. nov.

1895. Sciurus notatus Thomas and Hartert, Novitates Zoologicæ, II, p. 491. December, 1895 (part, specimens from Pulo Laut).

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).

Nine specimens, three from Sirhassen Island and six from Pulo Subi.

Those from Pulo Subi, while agreeing with the topotypes in color, appear to average a trifle smaller, though the series is hardly extensive enough to prove that this is constant.

RATUFA SIRHASSENENSIS (Bonhote).

1894. Sciurus bicolor albiceps Thomas and Hartert, Novitates Zoologicæ, I, p. 659. September, 1894 (Sirhassen).

1900. Ratufa ephippium sirhassenensis Bonhote, Ann. and Mag. Nat. Hist., 7th ser., V, p. 498. June, 1900 (Sirhassen).

Two specimens, Sirhassen, June 8, 1900.

This species, though related to Ratufa ephippium, with which it agrees in color-scheme, is sharply differentiated by its small size and cranial peculiarities. It is in no way closely allied to Ratufa bunguranensis and R. nanogigas.

As compared with that of Ratufa ephippium sandakanensis Bonhote, the skull in addition to its small size (greatest length 57 instead of 65) differs in general narrowness, in the relatively greater breadth of the nasal branches of the premaxillaries, and in the form of the audital bullæ. When the skull is held upside down and viewed from behind the bullæ are seen to be narrower than in the Bornean animal and to rise to a much greater height above the surface of the basi-occipital.

RATUFA BUNGURANENSIS (Thomas and Hartert).

1894. Sciurus bicolor bunguranensis Thomas and Hartert, Novitates Zoologicæ, I, p. 658. September, 1894 (Bunguran).

1895. Sciurus bicolor bunguranensis Thomas and Hartert, Novitates Zoologicæ, II, p. 491. December, 1895 (Bunguran).

1900. Ratufa ephippium bunguranensis Bonhote, Ann. and Mag. Nat. Hist., 7th ser., V, p. 497. June, 1900.

Thirteen specimens from Bunguran, all in various stages of the change from the bleached winter coat to the summer pelage. In the latter there is some color variation, mostly due to the greater or less distinctness of the drab wash overlying the Prouts-brown or 'chocolate' of the upper parts. Not only does the drab vary in amount in different individuals, but on every specimen it is more noticeable when the animal is viewed from in front. The drab wash is of the same character as that in Ratufa affinis, though less conspicuous.

As Mr. Thomas has pointed out to me, after examining a specimen of the latter, Ratufa bunguranensis is closely allied to R. pyrsonota. Indeed its relationship to the Siamese species is much closer than to the R. ephippium of Borneo. Together with R. pyrsonota the Bunguran giant squirrel differs conspicuously from that of Borneo in its narrow skull, lengthened audital bullæ, dark feet, dark median line on under surface of tail, and entirely brown back. From R. pyrsonota, however, it is readily separable by its darker, less ochraceous color both above and below, drab washed back, and by the much less distinct annulation of the hairs of the dorsal surface.

RATUFA NANOGIGAS (Thomas and Hartert).

1895. Sciurus bicolor nanogigas Thomas and Hartert, Novitates Zoologicæ, II, p. 491. December, 1895 (Pulo Laut).

1900. Ratufa ephippium nanogigas Bonhote, Ann. and Mag. Nat. Hist., 7th ser., V, p. 498. June, 1900 (Pulo Laut).

Four specimens, all from Pulo Laut, the type locality.

This strongly characterized dwarf species is allied to Ratufa pyrsonota and R. bunguranensis with which it agrees in color scheme. It is in no way closely related to the large Bornean R. ephippium.

RATUFA ANGUSTICEPS sp. nov.

Type.—Adult male (skin and skull) No. 104646 U. S. National Museum. Collected on Pulo Lingung, off south coast of Bunguran, June 17, 1900. Original number 481.

Characters.—Externally like Ratufa anambæ and R. melanopepla. Skull about equal to that of latter in length, but conspicuously narrower.

Color.—As