258 JOURNAL, BOMBAY NATURAL HIST. SOCIETY, Vol. XXV. 



two years old (^ of the extreme possible age) form 75 per cent, of 

 the total " population " ; individuals up to the three years limit 

 (half the extreme span of life) no less than 88"5 per cent. But 104 

 is, of course, far too perilously small a number to serve as a basis 

 for an age census, and I do not attach too much importance to the 

 percentages here arrived at, though it is a fact that they agree 

 veiy -well indeed with my experience as to the great abundance of 

 individuals with little or moderately worn teeth and the relative 

 scarcity of aged and senile individuals in any series of bats, of any 

 species. Twelve different localities are represented in this series of 

 104 specimens, but only in one single place was the oldest stage 

 (V) secured, 



Explanation of plate. 



All figures are of the subspecies Rliinolophus rouxi rouxi, and all 

 individuals are from October or November. Figures I — V repre- 

 sent the anterior upper molar (m') oi' the left side, viewed from the 

 surface and from the inner side, and in about 10 times natural size. 

 Those marked I are in the " first " stage of wear as defined in this 

 paper, those marked II in the second, and so on. In all figures, a 

 and h (and c, if present) are surface views, a' and h' (and c') inner 

 and somewhat oblique side views. Figures A and B (top of plate) 

 are given for the information of those who are not familiar with 

 the dentition and molar structure of this bat. 



Fig. A. — Palate view of left half of skull, to show dentition, ap, 

 anterior premolar ; pp, posterior premolar ; m^, first, m^, second, 

 m^, third molar. About 2-8 times natural size. ( $ ad., Se- 

 ringapatam, S. Mysore, 18th October, 1912, G.C.S. 1943). 

 Fig. B. — Anterior upper molar, left side, enlarged, to explain struc- 

 ture. 1, 2, and 3, the three cusps of the outer row ; 4- ^.nd 5, 

 the two cusps in the middle row ; 6, inner cusp ; 7, heel. 

 The commissures are marked co ; co. 1-4- is the commissure 

 between cusps 1 and 4 ; co. '2-4, the commissure between cusps 

 2 and 4 ; and so on. (Same specimen as fig. A.) 

 Fig. I. — First stage of wear (individuals about 6 months old), a 

 (surface view) and a' (inner side view) represent the minimum 

 of wear found in this stage ( 5 ad.; Seringapatam, S. Mysore, 

 18th October, 1912, G.C.S. 1943). h and />', maximum of wear 

 in this stage ( S ad. same place and date, G.C.S. 1949). 

 Fig. II. — Second stage (about 18 months old), a and a' minimum of 

 wear ( $ , Seringapatam, S. Mysore, 19th October, 1912, G.C.S. 

 1957). & and &', maximum of wear ($, same place, 18th 

 October 1912, G.C.S. 1939). 

 Fig. III. — Third stage (about 2\ years), a and a' , minimum of 

 of wear ( $ , Seringapatam, f8th October, 1912, G.C.S. 1937). 

 J> and h' , maximum ( § , same place and date, G.C.S. 1934). 



