380 Messrs. 0. Thomas and R. C. Wroughton on 



posterior tliird of the septum between them there are a pair of 

 liorizontal bony expansions projecting Laterally and partly 

 closing the foramina below. Palation just a little behind the 

 back of m^, level with the front edge of the parapterjgoid 

 fossae ; these fossce are broad and well defined anteriorly, but 

 posteriorly the ectopterygoids soon become obsolete. Bullae 

 of medium proportions. 



Incisors narrow, simple, flat or faintly concaye in front, but 

 they cannot be said to be grooved. Molars essentially as in 

 Ilus (comparison made with M. rattiis), but the pattern 

 rather more zigzagged, the median and lateral cusps higher 

 and the valleys between them deeper. No trace of postero- 

 internal secondary cusps, but on m^ there is a small antero- 

 external as well as the usual large antero-internal cusp. 

 Cusps of lower molars very upright, not or but little slanted 

 forwards ; minute extra cusps present externally between the 

 second and third laminpe of wj and the two laminas of m^, also 

 mesially at the hinder edge of both nii and m^ ; w?3 distinctly 

 bilaminate, the second lamina rather more than half the 

 breadth of the first. 



Type. Colomys GosJingi^ sp. n. 



Ihis striking genus has clearly no real relationship to the 

 other long-footed forms, Malacomys and Deomys, found in the 

 same region. Deomys is a member of the Dendiomyinse and 

 Malacomys has an elongated skull, different in almost every 

 detail from that of Colomys. 



We have therefore here a very interesting case of geogra- 

 phical isomorphism, three unrelated genera all showing the 

 same elongated metatarsi, and we trust that some observer 

 on the spot may be able to discover what special form of 

 surroundings has produced their common chfiracteristic. 



Colomys GosUngi, sp. n. 



About half the bulk of Mxis rattus. Fur short, rather 

 crisp and velvety in texture, but not spiny; hairs of back 

 7-8 mm. in length. General colour above between wood- 

 brown and cinnamon, a posterior dorsal area more blackened. 

 Under surface pure sharply defined white, the hairs white to 

 their bases ; line of demarcation very high on cheeks and 

 sides, fully halfway up the body, the white area taking in 

 the whole of the fore limbs, which are white throughout, but 

 the hind limbs have a narrow darker line running down 

 b.'hind them to the ankles. Ears fairly large, practically 

 naked, grey; a prominent white spot on the side of the head 

 below the notch. Upper surface of hands white, of feet 

 flesh-colour. Tail finely scaled, 12 scales to the centimetre, 



