464 MR. o. THOMAS ON A COLLECTION OK [June 17, 



6. Hesperomys (Calomys) bimaculatus, Waterh., var. 

 LEPiDUS, var. 11. (Plate XLII. tig. 2.) 



a to/. Six specimens. Jimin. 



Head and Forearm Ear- Muzzla 



body. Tail. Hind foot, and hand, conch. to ear. 



a. 6 7<J 34 17-0 240 14-5 20-8 



6. cJ 77 .. 17-8 24-1 14-5 203 



c. 6 70 38 17-5 223 137 19-0 



d. 6 68 3n 16-2 . 12-5 19-8 



e. 2 71 38 17-7 228 140 20-4 



/. 5 59 33 lG-2 21-0 122 18-0 



[Co-tvpe of] 



H'himacula-\ 3^ 50 16-2 20-4 12-2] 



tus ^ J 



Skulls. 



Total Basal Zygom. Molar luc. to Paint. Palat. Interorb. Basal Lower 

 length, length, breadth, series, ni'. length, foram. constr. axis. jaw. 



Of 4. c? 23-9 21-9 ISo 3 tj GO 11-9 ... 40 71 13 1 



e. $ 231 21-2 12-7 3-6 5-8 112 5-0 4-0 71 13U 



'•^tot~"} 2^'"* ••• ^^'^ ^'^ ^'^ ^^- ^'^ ^'^ ^ 



Fur remarkably long, soft and silky. General colour dull fawn, 

 somewhat darker on the centre of the back, through the inter- 

 mixture of numerous long black hairs. Fur all over the body slate- 

 coloured for three quarters of its length, the tips of the hairs yellow 

 on the upper surface and pure white on the belly. Feet and tail 

 wholly snowy white. 



Ears (Plate XLIV. fig. 12) very large, oval, without projection, 

 covered inside and out with short, yellowish-brown hairs ; laid 

 forward they reach considerably beyond the anterior canthus of 

 the eye. Tail uniformly hairy, the scales almost entirely hidden. 

 Soles (Plate XLIV. fig. 13) hairy for their proximal two thirds, the 

 pads small and crowded towards the distal end of the sole. Fifth 

 hind toe (without claw) reaching to the middle of the first phalanx 

 of the fourth. Claws very small, both before and behind, almost 

 buried in the hair on the toes. Mammae 8 — two pectoral and two 

 inguinal pairs. Interdental palate-ridges five in number. 



Skull light and delicate ; frontal outhne markedly convex ; supra- 

 orbital edges square, but not ridged. Interparietal very narrow 

 antero-posleriorly, but stretching right across the skull. Palatal 

 foramen longer than molar series. 



This variety may be distinguished from the true H. bimaculatus, 

 Waterh.^, by its rather larger size, much longer and differently 

 shaped ears (see Plate XLIV. figs. 12 & 14), its shorter tail, much 

 longer fur, slate-mixed instead of pure-white belly, and by the entire 

 absence of supraorbital ridges on its skull. Comparative measure- 

 ments both of spirit-specimens and skulls are given above. 



There are in the collection six specimens of this form, which is 

 interesting as belonging to tiie rare and little-known subgenus 



' P. Z. R. 1837, p. 10 ; VoT. ' BesglK,' Mamm. p. 4.-!, pi. 12 (1839). 



