DETEliMiyATWHi OF A(n: I\ /iAT!^. i'r,l 



they show all stages of wear, possibly (not certainly) witli fxceji- 

 tion of an extreme senile stage. It has fiu'ther the advantage oJ' 

 being from (October and November, thus containing a good number 

 of individuals just adult (supposing the young ot this species, in 

 that particular region of India, to be born in April or May, which, 

 judging from ihe foetuses I have seen, they probably are, as ;i 

 rule), showing the llrst stage of wear, that of adult specimens abouf. 

 six months old. It further contains sixty-four adult specimens 

 from the same zoogeographical area, not from the ten other months 

 of the year, but from four (January, F(0)ruary, April and ^lay). 

 sufficientl}^ distant to check the results derived from the October 

 November series. 



Those not familiar with the molar structure of a l\hinolophiii< 

 shoxild examine fig. B, on the plate accompanying this paper, and 

 the explanation of that figure on p. 258. before proceeding to read 

 the next paragraph. 



The different i^ttuje^ of v;ear of ihe anterior upper vnolar in 

 Odoher-Novem her individ u ols. 



First stage (fig. I). — The molars in this stage are so little worii 

 tliat it requires some care, and often the use of a good pocket lens 

 (or better still, a dermatoscope), to discovei- the traces of wear. 

 The commissures (1-4, 2-4, 2-5, and 3-5 ; see fig. B) are no longei 

 absohitely sharp-edged, as in the perfectly unworn tooth ; that is, 

 they show, not one single line (like a razor edge), but distinctly 

 two sub-parallel lines very close together, and between these lines 

 an exceedingly narrow sublinear flattened edge. Similarly, the ridge 

 of cusp G is not single-edged, but shows two more or less parallel 

 lines ; its central portion is aiwaj's a little more worn than the ridge 

 in front of and behind it, because it, being the highest point of the 

 ridge, is more energetically acted upon by the corresponding tooth 

 of the lower jaw (cusp 5 of m^). Viewed in profile from the inner 

 side (a' and b') cusps 4' and 5 will be seen to be not absolutely 

 shai-p-pointed, but alreadj- with the points slightly blunt. 



The individual variation in the degree of wear at this stage is 

 small. Figs. la and a' show the minimum, figs. 1 b and b' the 

 maximum amonor eleven individuals from the months of Octobei- 

 and November. 



Second stage (fig. II). — The worn edges of the commissui*es are 

 in this stage twice to three times as broad as in stage I ; the breadtli 

 (side to side) of the worn edge of cusp 5 is almost 1/2, or in 

 any case nearer 1/2 than 1/3 (in stage I roughly 1/4) of the total 

 length of commissure 2-5, The worn edge of cusp 6 begins now 

 to assume in its central portion a pronounced subtriangular (irre- 

 gularly triangular) shape, but is still sublinear in front of and 



