152 ON SMALL MAMMALS FROM DEMERARA. [Feb. 15, 



7. Hesperomys (Rhipidomys) sclateri, sp. n. (Plate XIX.) 



a. 5 . Maccasseema. 1 1/86. 



"I am sorry to say I caunot remember anything about the habits 

 of this Rat ; it was caught aud brought to me by one of Mr. im 

 Thurn's Indians, and of course did not live in tlie house." 



Fur short, close, very soft and velvety. General colour uniform dark 

 ashy grey, the tijis of the hairs below white or pale rufous, line of 

 demarcation not strongly marked ; bases of all the hairs slate- 

 coloured. Hairs on both fore aud hind feet, including the fingers 

 and toes, all dark brown or black. Ears, when laid forward, reaching 

 just to the centre of the eye ; no projection on their anterior border ; 

 tlieir backs hairy, black. Tail long, uniformly black, thickly hairy, 

 the hairs about 3 or 4 mm. long throughout, except just at the base, 

 where they are shorter, and at the extreme tip, where they are 10 or 

 12 mm. long; the rings of scales well-marked, 15 or 16 to the 

 centimetre. INIammse 6, one axillary and two inguinal pairs. Inter- 

 dental palate-ridges 6. Foot-pads broad, smooth, rounded ; soles 

 naked, quite smooth. 



Skull exceedingly similar to that of H. leucodactylus, Tscb. 

 (figured P. Z. S. 1884, pi. xliv. fig. 8), but rather longer and nar- 

 rower, especially in the cranial portion, with the supraorbital edges 

 more strongly developed, and with the incisors rather longer and 

 heavier. 



Dimensions of the type, an adult female in spirit : — Head and 

 body 133 mm., tail 1/2, hind foot 33, forearm and hand 39, ear, 

 above crown, 16, head 43, muzzle to eye 18'5. 



Skull. Basal length 31-5, greatest breadth 19; nasals, length 

 12-8; length of molar series 6-4; back of incisors to front of 

 m^ 102; palatine foramen, length 8-0; interorbital constriction 

 6-3. 



This species, with which I am glad to connect the name of its dis- 

 coverer and donor, is very closely allied, in all its essential characters, 

 to H. (^Rhipidomys) leucodactylus, Tscb.-, but that s])ecies has its fur 

 very much the nature, colour, and texture of that of the Common 

 Rat ; while in //. sclateri tlie fur is wholly difTerent to this, being in 

 tact more like that of certain of the smaller Opossums in its soft and 

 velvety character. In //. sclateri the colour is also darker and more 

 uniform than in H. leucodactylus, the tail is more uniformly busliy, 

 and the feet, both fore and hind, differ by having black-haired 

 instead of pure white toes. 



The present is the first recorded occurrence of any member of the 

 interesting Dormouse-like subgenus Rhipidomys in the region north 

 of the Amazons and east of Colombia, and gives therefore a very 

 important addition to the known range of the subgenus. Other 

 species have beeu recorded from Central America, Ecuador, Peru, 

 Bahia, and jNIinas Geraes, the nearest ally of //. sclateri being, as 

 already noted, the Peruvian H. leucodactylus, Tscb. 



2 Fauu. Peruana, p. 183, pi. xiii. fig. 2 (1844). 



