254 On new Forms of Saimiri, Saccopteryx, &c. 



Thrichomys laurentius, sp. n. 



Closely allied to T. apereoides, but greyer and with less 

 tufted tail. 



Fur close and straight, rather shorter than in T. apereoides; 

 hairs of back about 18-20 mm. in length. General colour 

 above approximately " broccoli-brown," the individual hairs 

 slaty grey below, paler at base, darkening outwards, with a buffy 

 subterminal band and a black tip. Sides, especially shoulders 

 and hips, paler and greyer. Under surface, except for a 

 greyish collar, pure sharply defined white, the hairs white to 

 their bases. Head dark grey, a whitish spot above eye, 

 another below it, and a third at outer base of ear. Long 

 hairs o£ ear black. Arms and legs greyish, like sides ex- 

 ternally, white on their inner aspects ; hands and feet mixed 

 grey and white along the metapodials, pure white laterally and 

 on the digits. Tail with about an inch at its base clothed 

 with hair of the texture and colour of that on the rump ; the 

 remainder cylindrical, well-haired, but not markedly crested 

 above, and the hairs scarcely increasing in length terminally, 

 the longest hairs barely attaining 8 mm. In T. apereoides the 

 upper surface is crested with hairs which increase in length 

 to the end, where they attain 15-18 mm. Colour of tail 

 black above and at the end, dull whitish proximally below. 



Skull on the whole as in T. apereoides, but the nasals are 

 longer and the palatal foramina are more widely open, in 

 this respect approaching those of T. Fosteri. Last molars 

 similar to those of T. apereoides, less complicated than is 

 usually the case in T. Fosteri. 



Dimensions of the type (measured in the flesh) : — 



Head and body 215 ram. ; tail 195 ; hind foot (s. u.) 45 ; 



ear 21. 



Skull : greatest length 56*7 ; basilar length 41 ; greatest 

 breadth 26; nasals 20 , 5x6 , 5; interorbital breadth 11-3; 

 breadth across postorbital projections 17*2 ; palate length 

 19-8 ; diastema 11; palatal foramina 5'8 X 4*4 ; length of 

 upper molar series 8*6. 



Hob. Sao Lourenc/), near Pernambuco. Alt. 50 m. 



Type. Old male. B.M. no. 3. 10. 1. 68. Original number 

 1721. Collected 16 August, 1903, by Alphonse Robert. 



By the discovery of the present animal the range of the 

 genus Thrichomys is very considerably extended. Till 

 recently only recorded from Lagoa Santa (Lund and Rein- 

 hardt), it was found in Paraguay by Mr. W. Foster, who 

 has now sent a considerable series of the local species to 

 the British Museum. In that country it is found only " in 



