272 Mr. O. Thomas on 



Skull of tlic shape typical of the genus, but distinguished 

 from that of most of the species by its small size. Nasals 

 narrow, just surpassing the premaxilljB posteriorly. Inter- 

 orbital space flat, its edges with well-developed divergent 

 ridges which can be traced backward across the parietals to 

 the outer corners of the interjiarictal. Brain-case broad and 

 rounded. Palatal foramina short, barely reaching backward 

 to the level of the front of i)i}. Molars very small, smaller 

 in proportion than in other species. 



Dimensions of the type (an adult female, measured in 

 the flesh by collector) : — 



Head and body 100 millim. ; tail 120; hind foot 22; 

 car 14. 



Skull : extreme length 27 ; basilar length 20"o ; greatest 

 breadth 15; nasals 9'3x3"l; interorbital breadth 5"2 ; 

 breadth of brain-case 12*2; palate length from henselion 11 ; 

 diastema 7; palatal foramina 4'6x2'2; length of upper 

 molar series 3"8. 



Bab. Paramba, N. P^cuador. Alt. 1100 m. 



Ti/pe. B.M. no. 99. 12. 5. 4. Original number 12. Col- 

 lected 11th Ma}', 1899, by R. JMiketta. Two specimens 

 examined. 



This striking little species, one of the smallest of the genus, 

 has a certain resemblance to B. microtis^ Thos., from the 

 neighbourhood of Bogota, but is readily distinguished by its 

 brighter colour, pure white belly, and much smaller palatal 

 foramina and molars. 



Its nearest ally is probably Tomes's " Ilesperovii/s hicolor " *, 

 collected by Fraser in the Ecuadorean Oriente at Gualaquiza ; 

 but that animal is said to have a " darkish cinnamon-brown " 

 general colour, and its under surface is yellowish white. The 

 tail is also shorter than the head and body. 



Oryzomys sylvaticus, sp. n. 



General appearance very much that of a large specimen of 

 the European Mus syhaticus. Fur straight, close and rather 

 crisp, about 8-9 millim. long on the back. General colour 

 above dull fulvous, much darkened with black on the middle 

 line of the back, clearer on the sides. Htad decidedly greyer 

 than body. Under surface soiled whitish, the bases of the 

 iiairs slaty, the tii)S dull white ; line of demarcation on sides 

 rather sharj)ly defined. Ears large, finely haired, dull brown. 

 Outer sides of limbs greyish, inner sides like belly ; hands 

 and feet dull white above, wrists and ankles browner ; feet 



* P. Z. S. 1860, p. 217. 



