108 Mr. 0. Thomas on neid 



close beliind back of in^^ the mesopterygoid fossa broad* 

 BuUge rather small. 



Incisors of medium development, their front surface flat, 

 ungrooved. ISIolars, so far as the enumeration of cusps is 

 concerned, as in Saccostomus and other Dendromyinfe, with the 

 important exception that the postero-interiial cusp of in} 

 (the X cusp) found in certain genera of Murine — e. g. Tham- 

 vomi/s — is here also present, the cusp-formula of the three 

 laminae of m^ being therefore the unique one of 2.3.3, Mus 

 having 3.3.2, Thamnomys 3.3.3, ordinary Dendromyinse 

 2.3.2. 



Individually the teeth are highly cuspidate, the cusps well 

 separated and distinct. On both m^ and m^ the postero- 

 internal and postero-external cusps are united to each other 

 by an enamel ridge passing round behind the main middle 

 posterior cusp. M^ consists of two simple distinct trans- 

 verse lamina?. 



Below, the teeth have well-developed supplementary 

 external ridges, and both 7??i and w^ have distinct median 

 posterior supplementary cusps. 



This genus is readily distinguished by the above characters 

 from any previously described. Its possession of only two 

 cusps on the anterior lamina of m^ separates it from the great 

 mass of African Muridas, which have three, while from those 

 which have two it is equally distinguished by having three 

 cusps on the third lamina. Its general characters are also 

 quite distinctive, and it is not easy to say to which of the 

 older known genera it is most nearly allied. Perhaps 

 Saccostomus is the nearest, but the differences are so great 

 that the alliance is very remote. 



Externally the animal may be at once i-ecognized by its 

 curious naked white-tipped tail of medium length, neither 

 shortened as in Saccostomus, Steatomys, and Malacothrix, 

 nor lengthened as in otlier members of the group. The feet 

 are particularly short, and therein contrast with those of 

 Deomys and other aberrant African genera. 



Beamys hindei, sp. n. 



Size that of a medium Mus. Fur soft and fine ; hairs of 

 back about 10 mm. in length. General colour, so far as can 

 be made out on a spirit-specimen, very much that of Sacco- 

 stomus campesf.ris, uniform greyish or greyish brown above, 

 pure white below. Ears not large, laid forward, in a spirit- 

 specimen, they only just reach the posterior canthus of the 

 eye, rounded, almost naked, greyish. 



