7 : HystTrix. 363 
Dr. Kellaart, who was a most careful observer, has been of great assist- 
ance to me in the above, as it was also, I fancy, to Jerdon, and his subse- 
quent remarks are worthy of consideration. “The identification of 
species from single characters,” he observes, “‘is at all times difficult and 
unsatisfactory in the genus /ystvix, particularly so as regard the con- 
formation of the skull.” And again: “ The number of molars varies 
also in different specimens. In two adults obtained at Trincomalee 
there were only three molars on each side of the jaw, four being the 
dental formula of the genus Aystrix.” 
ay x 
WF ee / - 
— SA raw Ge 
= ai ea SS KW = oo SD NINN eee 9 
Bo, ~<— SSS ae 4 re 
rth - ) oS Bas = 
ren ys —— = 2 
Lffystrix leucura. 
I think such aberrations ought to warn us from trying to make too many 
genera out of these animals. Dr. Gray, whose particular forte—or shall 
I say weakness ?>—was minute subdivision, classed (in 1847) the Indian 
porcupines in three sub-families, Aystrix, Acanthion, and Atherura ; 
and Acanthion he some years after (1866, see ‘P. Z. S.’ p. 308) divided 
again into three groups, Cidocephalus, Acanthocherus and Acanthion. 
The difference in the skull of Aystrix and Acanthion lies in the inter- 
maxillaries and the grinders, as follows :— 
HHystrix—Inter-max. broad, truncated, wide behind as before ; grinders 
