Mr. O. Thomas on African Rodents. 223 



In East Africa the type of L. testudo, Thos.,was obtained 

 by Mr. F.J.Jackson at Ravine Station, and other speci- 

 mens have since been referred to it. But now examination 

 proves that the type remains unique, and that all the other 

 E. African specimens available belong to a larger species 

 closely allied to the Abyssinian one and itself divisible into 

 two subspecies. 



Subjoined are the diagnostic characters of the four species 

 which at present appear to be recognizable. 



In drawing them up I have had for examination two 

 specimens of L. imhausi, two of L.bozasi (including one skull 

 belonging to the United States National Museum), six of 

 L. ibeanus (including a U.S.N.M. skull from Nakuru), and 

 one — the type — of L. testudo. 



Size comparatively large. Frontal region con- 

 cave. Mesopterygoid fossa long. Ante- 

 orbital foramen high, narrow, slit-like. Pala- 

 tal foramina long. Sides of premaxillse not 

 or scarcely granulated, except along the edge 

 bordering the nasals. (Abyssinia.) 



L. bozasi, Oust, (probably L. cethiopicus, Peters). 

 Size variable. Frontal region more normal. 

 Mesopterygoid fossa long. Anteorbital fora- 

 men larger and more open ; its outer edge 

 thickened into a ridge, with a large masse- 

 teric knob at its lower end. Palatal foramina 

 shorter. Sides of premaxillre heavily granu- 

 lated, especially in the fossa just above the 



incisors. (British E. Africa.) L. ibeanus, sp. n. 



Size and teeth smaller. (Mau Region.) L. ibeanus ibeanus. 



Size and teeth larger. (Aberdare Range.) ...... L.i. hindei, subsp. u. 



Size smaller. Mesopterygoid fossa very short. 

 Anteorbital foramen very small, low, well 

 open, its outer edge practically without 

 strongly marked ridge or masseteric knob. 

 Nasals markedly narrowed in their posterior 

 half, parallel-sided in all the other forms. 

 Incisors narrow, dead white in front, cream- 

 coloured in other species. Line of glandular 

 biistles on sides narrower and less con- 

 spicuous than in other species. (British E. 



Africa.) L. testu-lo, Thos. 



Size smallest. Mesopterygoid fossa long. Ante- 

 orbital foramen comparatively large, well 

 open, its edge ridged and with well-marked 

 masseteric knob. Frontal region promi- 

 nently white, grey in the other species. 

 (Somali-land.) .... L. imhausi, M.-Edw. (syn. L. smithi, Rhoads). 



The following are the chief diagnostic measurements of 

 the skulls : — 



