the Genus Otomys. 269 



The following may be taken as normal dimensions for this 

 species : — 



Head and body 145 mm. ; tail 80 ; hind foot 25 ; car 17. 



Skull: fjrcatcst Icnjijth 38 ; basilar length 30; zygomatic 

 breadth 20; length of upi)er molar series 7; bulhc 11. 



In all the individuals of this suljspccies, quoted abovCj the 

 niodlHcation of the first two laminae o£ the anterior lower 

 molar shows distinctly the " spiral " pattern. 



(3) Otomys unisulcatus. 

 Otomys unisulcntus, Cuvier, Mamm. 18:29, pi. cclxiv. 



41.805, 41.806 (skull 59.5.7.2). S. Africa {Dr. A. 

 S)ni//i). 



There is unfortunately no really satisfactory specimen of 

 unisulcatus in the Natural History jNluscuni collection. It 

 is probable that the above are the specimens on which 

 Dr. Smith based his description of unisulcatus (Zool. S. A. 

 pi. xxiii.). Basing on these and on this description, the 

 following may be taken as normal dimensions of this 

 species : — 



Head and body 175 mm. ; tail 90; hind foot 25; ear (no 

 data) . 



Skull: greatest length 38; basilar length 30; zygomatic 

 breadth 21 ; length of upper molar series 8. 



The shorter tail and hind foot and a much warmer 

 colouring seem to be the chief characters distinguishing this 

 species from unisulcatus Broomi, while its larger size and much 

 shorter tail differentiate it from unisulcatus Granti. 



m^ (in this and the following members of this group) is 

 composed of three complete laniinse and a posterior portion 

 in the shape of a trefoil ; in unisulcatus the modified anterior 

 portion of wij shows a " kidney "-shaped pattern. 



(4) Otomys unisulcatus Broomi. 



Otomys Broo7ni, Thos. Ann. & Mag. Nat. Hist. vol. x. p. 313 (1002). 



98. 9. 3. 3-4. Port Nolloth, Namaqualand [R. Broom) . 



4. 2. 3. 75. Klipfonteiu, Namaqualaud. Alt. 3104'. 

 (Rudd Exploration.) 



The normal dimensions for this species are : — 



Head and body 160 mm. ; tail 105 ; hind foot 28; ear 24. 



Skull: greatest length 38; basilar length 31; zygomatic 

 breadth 18 ; length of upper molar series 8 ; bullae 8. 



This form differs from typical unisulcatus by its paler, less 

 rufous colouring aud its rather larger hind foot^ ears^ and 



