1807.] NEW AFRICAN MAMMALS 433 



maxillarjr processes slender, surpassing the nasals by about 5 mm. 

 Frontal narrow, flat, without the peculiar hollows just inwards of 

 the postorbital processes found in the allied species. Postorbital 

 processes well-developed, succeeded behind by a deep notch, follow- 

 ing which there is a strongly developed supplementary process on 

 the squamosal. Brain-case comparatively long, much narrower 

 than in (jregorianus. Anteorbital foramina high and open, the 

 bony bridge over them comparatively slender ; front edge of their 

 outer wall nearly vertical. Malar less vertically produced than in 

 gregorianus. Teeth apparently as in gregorianus, but too much 

 worn for exact comparison. Posterior palate extending about 

 3 mm. behind the molars. 



Dimensions of the type, an aged female, in skin : — 



Head and body 420 mm. ; tail (imperfect at tip) 110 -|-? ; hind 

 foot 63. 



Skull — basal length 69, basilar length 61 ; greatest breadth 53 ; 

 nasals 28 x 14 ; interorbital breadth 25 ; tip to tip of postorbital 

 processes 30 ; intertemporal breadth 24 ; least breadth across 

 brain-case behind zygomata 28*5 ; greatest ditto 37 ; palate-length 

 from henselion 34 ; diastema 17 ; length of upper molar series 14. 



Hab. Nyika plateau, 6000-7000 ft. 



Mr. Thomas had named this interesting animal in honour of 

 Mr. Sclater, at whose instigation the Nyasa explorations had been 

 begun, and to whose efforts so much of their continued success 

 had been due. 



T. sclateri was unquestionably most nearly allied to the species 

 discovered by Dr. Gregory in Kikuyu, from which region 

 Mr. Jackson had recently sent the skin of a young example. This 

 skin had a yellow throat, yellow inner sides of both fore and hind 

 limbs, and yellow groins, these parts being white in T. sclateri. 

 Its fur was rather stiffer than in T. sclateri, and its tail was 

 scarcely longer than the hind foot, a character which if constant 

 in the adult would form a good external mark of distinction 

 between the two forms. 



With regard to Gerhillus boJimi, Noack, of which two specimens 

 were in the collection, Mr. Thomas thought the difference in the 

 character of the incisors from that found in typical Gerhillus rendered 

 it convenient to form a special subgenus for the reception of the 

 species, and this he proposed to call Gerbilliscus. As poiuted out 

 by Dr. Noack, the incisors had two very shallow and almost 

 indistinguishable grooves on their faces, instead of the single deep 

 groove found in all the true Gerbilles. 



Mr. Thomas also stated that an examination of a Petrodromus 

 from Zomba in the collection had convinced him that, instead of 

 containing only a single species, the genus might be readily divided 

 into three species — one from Mombasa, Mandera, and the neigh- 

 bouring parts of E. Africa proper ; one from the Eovuma Eiver ; 

 and the third from the Zambesi and Shire Elvers. The last 

 named might be considered the typical form, as whatever Peters's 



