2o4 JOURNAL, BOMBAY NATURAL HIST. SOCIETY, Vol. XXV. 



course only to determine the age of the individuals of the first 

 stage, which will give ns at once the age of each of the subsequent 

 stages. As to that question there is no uncertainty at all. The 

 actual degree of wear in this first stage would be sufficient to tell 

 us that the individuals can be only just adult, that is (supposing 

 they were born in April or May) about six months old. This con- 

 clusion is further supported by the fact that in the case of five 

 individuals in this stage I am able to say, on the strength of cer- 

 tain external characters, that they are " bats of the years."* 



We are thus enabled to fix the ages of our October and Novem- 

 ber individuals as follows : — First stage, about 6 months ; second, 

 about 18 months ; third, about 2^ years ; fourth, about 3^ 

 years ; fifth, about 44 years. If to this we add a minimum 

 of half a year and (supposing that a sixth stage does occur occa- 

 sionally) a maximum of a year and a half, we arrive at five or six 

 years as the extreme possible age of this bat. If one should have 

 nazai'ded a simple guess at the probable age limit of a bat of this 

 size, it would have been very much the same. 



Strictly speaking, both the facts and the conclusions recorded 

 above are, of coui'se, only valid for Rli. rouxi, or more narrowly 

 still for individuals of this species from South and Central India. 

 [ should think, however, that other bats of about the same size, 

 with the same molar structure, and dependent on a similar diet, 

 would not differ very much in this respect. 



My object has been to determine the probable age of each in- 

 dividual in the series under consideration, and I have therefore 

 confined myself to what was necessary for this purpose. To grasp 

 the alterations taking place, from year to year, in a single tooth is 

 really all that is needed, and by focussing the attention on one 

 tooth, rather than describing in detail the alterations by wear in 

 the whole tooth row, I hope I have made my paper not only much 

 shorter, but clearer as well, and the facts more easy to remember. 

 Still I ought perhaps in conclusion to add a few words about the 

 other teeth. 



The first upper molar is one of the teeth best suited for our 

 present purpose ; it is one of the most complicated in structure, 

 and therefore shows most readily the effects of wear. The second 

 molar differs in no very important point from the first, and might 

 almost as well have been selected for description here ; the surface 

 wear affects it very nearly in the same way, and it reveals the age 



• They are individuals who had just completed their first (autumn) moult, 

 and the new coat of which was changin}? from the dark to the firsc (auburn) 

 " I)hase". Their numbers are 194:5 and 1947-1950, all from iSeringapatam, !?outh 

 Mysore, 18th October 1911. (See the paper already referred to, on the colour 

 phases of Bh. rouxi.) 



