216 MR. R. I. POCOCK ON THE 



fepi'esented on the lower side of the tip hy grooves running 

 obliquely backwards and inwards towards the middle line. It 

 was clearly, I think, to a Squirrel of this genus, possibly indeed to 

 tristriatus, that the gians penis figured and described by Tullberg 

 as that of palmarum belonged. His figure, however, does not 

 show such a definite lower lip as was present in the example from 

 Malabar above described, the area beneath the upper lip being 

 supplied with two rows of lobules representing the subdivisions 

 of the lower lip in my specimen. (Text-fig. 18, D.) 



The difference between F. j^cdmarimn and T^ tristriatus in the 

 structure of the penis is reflected in the shape of the baculum, 

 which in T. tristriatus, instead of being gradually curved upwards 

 from base to apex, has the proximal three-fourths curved towards 

 the right with the right side concave, the left convex, and the 

 distal fourth bent up at a right angle to form a vertical branch 

 with an ex])a.nded tip, a conA^ex crested posterior edge and a 

 concave anterior edge. From the inferior angle of this arises a 

 much smaller branch directed downwards. This description is 

 taken from a baculum, measuring 11'5 mm., taken from a specimen 

 of tristriatus from Helwak, Satara, and preserved in the British 

 Museum. Another baculum in that collection, taken from an 

 unidentified specimen without locality, differs in having a less 

 expanded apex to the upper branch, no crest on the latter and no 

 inferior branch, the shaft being straight. It measures 1 1 mm., and 

 may represent a different race or species. (Text-fig. 20, A, B, C.) 



In the example from Malabar of which the glans penis was 

 described, the apex of the upper branch projected a little way 

 into the upper lip of the glans, and the lower branch formed the 

 bulge at the inferior part of the base of the lower lip. The 

 baculum, measuring 12 mm., is similar in curvature and other 

 particulars to that of the example from Satara, except that the 

 inferior branch is more quadrate and not hook-like. 



The two genera of Oriental Squirrels described above are a most 

 instructive instance of close superficial resemblance associated 

 with great differences in the glans penis and baculum. They are 

 so much alike that Blanford was doubtful if tristriatus was more 

 than what he would have called a "variety" of palmaruvi. Yet 

 it is impossible to believe in close kinship between them ; and the 

 difierences explain the occurrence of the two in the same districts 

 in India without ever inter-gxading — that, at all events, I believe 

 to be the case. 



The structural characters of the two may be recapitulated as 

 follows : — 



a. Glans penis ending distally in a narrow elongated point supported 

 by tlie distal portion of tlie baculum ; the orifice on the right 

 side near the base of the slender portion and remote from the tip 

 of the glans. Baculum a simple upcurved attenuated rod Fimamlmhis. 



a'. Glans penis thick, blunted, and bilabiate distally, the orifice 

 terminal between the upper and lower lips, the lower lip 

 secondarily subdivided. Baculum with its terminal portion 

 bent vertically upwards and curved forwards, with a pro- 

 minent inferior angle Tamiodes. 



