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Show 1906.] MAMMALS FROM BECHUANALAND. 109 the claws. Tail shorter than the head and body ; covered above and below with short white hair, except on the upper surface for a space of about 10 m m . at the distal end, where it is black ; tip not tufted; scale-rings numbering about 33 to 1 cm. : mamma? three pairs pectoral, and 2 pairs inguinal. Skull smooth and rounded, not ridged. No supraorbital edges, only a faint indication of ridges on the parietals. Anterior edge of anteorbital plate shows considerable variation from strong convexity to being nearly straight. Palatal foramina widely open, of medium length, ending opposite the anterior lamina of m1; palate ending 05 mm. behind m3. Bullae of medium size. Incisors not visible beyond the nasals when viewed from above, orange in the upper jaw, light yellow in the lower. Molars of medium size, broad with well-defined cusps. Anterior median cusp of m 1 larger than the two posterior ones, partly fused with the antero-external cusp. M3 is a simple circular tooth with one large antero-internal cusp. The simplicity of this tooth is very remarkable and quite different from the typical arrangement found in M. rattiis. Dimensions of the type (measured in the flesh) :-Head and body 138 mm.; tail 122 ; hind foot 26'5 ; ear 20'5. Skull:-Greatest length 35; basilar length 29'4 ; zygomatic breadth 17*8; nasals 14x3*6; interorbital breadth 4 2 ; brain-case breadth 13; interparietal 4*4x9'4; henselion to back of palate 16-3; palatine foramina 7*6; diastema 10; upper molar series 5*7 ; mandible, height at coronoid 10*7 ; incisor tips to condyle 24-8. Hab. Molopo, Bechuanaland. Type. Male. B.M. no. 4.10.1.83. Original number 86. Collected 13th July, 1904. This very distinct species is unlike any rat hitherto known, both in colour and in the structure of the third upper molar. 1 have much pleasure in naming it after Mr. R. B. Woosnam, to whose efforts in company with Mr. R. E. Dent the British Museum is indebted for this very interesting collection. " These rats from Kuruman were trapped in the bush-veldt about half a mile from the river in the mouth of a small hole in a 'wait-a-bit' thorn-bush. Unfortunately the black ants damaged a good many of the animals in the traps. At Molopo this rat seemed to be confined to the river pools."-R. B. W. 19. Mus sp. o*. D. 132. 2 • D. 141. Kuruman. o*. W . 74, 75, 84, 89, 22, 93, 100. $ . W . 85, 90. Molopo. Owing to the absence of adult females in the series I am unable to ascertain the mammary formula of this animal, a factor of great importance in deciding the specific position of mice in the Mus concha or colonics groups. " These mice are very plentiful among the long dry grass by the Molopo River and in the forest on the banks."-R. B. W. |