596 



SCIENTIFIC KESULTS FROM THE MAMMAL SUEYEY. 



No. XXV. 



BY 



Oldfield Thomas. 

 {Published by permission of the Trustees of the British Museum) 



(A). ON JUNGLE-MICE FROM ASSAM. 



The Collections made by Mr. Wells in Assam include a number 

 of Jungle-mice wbich seem to be referable to three species, readily 

 distinguishable by size. 



The largest is one allied to the Sikkim species I described as Mus 

 jjahari, but which, on the conclusions given in the later paper on 

 the grouping of Indian Mice (Results No. xix ; J. B. N. H. S. xxvi., 

 p. 417, 1919) and followed in Mr. Wroughton's Synopsis (Part v, 

 Journ. c. p. 957, 1920) now falls into the genus Leggada. The 

 Assam form is however smaller, less dark, and differs by at least 

 one important cranial character. 



It may be called 



Leggada jacksoni^, sp. n. 



Size rather less than in pahari. Fur profusely mixed with spines, 

 though perhaps rather less so than pahari ; dorsal spines about 

 8mm. long by 0' 2mm. broad. General colur above dark mouse grey, 

 not so dark as in pahari, undersurf ace dull brownish white, the 

 coloration generally not unlike that of Mies musculus. Ears rather 

 large, brown. Hands and feet white. Tail about the length of the 

 head and body, or a little shorter, brown above, dull whitish below, 

 scales 18 to the centimeter. 



Skull in its general shape very like that of L. pahari, with the same 

 long muzzle, the supraorbital angles however not so strongly marked. 

 Zygomatic plate narrow, its front edge slanting straight downwards 

 without any trace of forward convexity ; this character is equally 

 marked in specimens of all ages, while in pahari the front 

 edge always projects ; masseteric knob scarcely perceptible. Palatal 

 foramina short, not reaching to the level of the front root of m^ . 



Incisors as in pahari, thick and markedly opisthodont ; index 

 about 66°. 



Dimensions of the type, measured in the flesh : — 



Head and body, 90mm. ; tail 83 ; hindfoot 19 ; ear 15"5. 



Skull, greatest length 24-2 ; condylo-incisive length 22*2 ; 

 zygomatic breadth 11"7 ; nasals 9*2 ; interorbital breadth 4*7 ; breadth 

 of braincase 11'2 ; zygomatic plate 2 ; palatilar length 10 ; palatal 

 foramina 4*6 ; post-foraminal palate 4*6 ; upper molar series 3.6. 



Hab. — Khasi and Garo Hills, Assam. Type from Laitkynsao, 

 Khasi Hills. Others from Tura, Garo Hills. 



