66 Records of the Indian Miiseum. [Vol. XY, 



Dr. Annandale admits, deviations from the more normal pattern pre- 

 served in R. cancrivora ; and therefore I do not think that the case in 

 question points to forms originally distinct having converged to resemble 

 each other in the adult condition. My opinion is supported by various 

 examples, drawn from other types of animals, which Giard (1891-1892) 

 has grouped together under the term poecilogony, the list of which is 

 constantly being increased. 



I am glad my remarks have led Dr. Annandale to procure further 

 material of the Bull-frog which occurs commonly in India and Ceylon ; 

 I only regret he has not had more before expressing a decided opinion 

 on the two forms the distinction of which I have pointed out. These 

 he now regards as valid species, a divergence of view which may appear 

 to some to be merely a matter of opinion. I wish, however, to observe 

 that I feel sure a larger series would have convinced him that inter- 

 mediate specimens fill up the gap between the extremes shown by his 

 text-figures. To mention only one example, the specimen from Ceylon 

 of which measurements are given in column 10 of my table under R. 

 tigrina typica has the metatarsal tubercle in an exactly intermediate 

 condition as regards shape and size. 



I have only seen a few living specimens of the Indian frogs, but in 

 dealing with the European R. esculenta I have carefully studied enormous 

 numbers, many caught by myself, and I may appeal to experience thus 

 gained, as the distinction between the typical R. esculenta and the var. 

 lessonae is a perfect parallel to the case of R. tigrina and R. crassa. The 

 difference between the two extremes, in the proportions of the hind limbs 

 and in the size and shape of the metatarsal tubercle is the same, as may 

 be realized from the following measurements (a, length from snout to 

 vent ; h, length of tibia ; c, inner toe, measured from the metatarsal 

 tubercle ; d, length of metatarsal tubercle ; e, perpendicular diameter 

 of the tubercle) : — 



a. b. c. d. e. 



R. esculenta typica, Nice ... 74 37 10 4 1 



li. esculenta var. lessonae, Norfolk 72 29 8 6 2-5 



I add the same measurements of a R. crassa, from the Madras Presi- 

 sency, presented under that name to the British Museum by Dr. Jerdon, 

 which show the inner metatarsal tubercle to be even smaller, in propor- 

 tion, than that in the R. escidenta var. lessonae, from Norfolk : — 



E. tigrina var. crassa ... ... 90 42 9 6 2-5 



Now it is perfectly well known that there is so complete a gradation 

 between the two extremes indicated by the above measurements that 

 not even the extremists in species multiplication, of which we have a 

 few among European herpetologists, have ventured to separate the form 

 lessonae as a species. I have not the least doubt that if a large number 

 of specimens could be obtained, from Ceylon for instance, and carefully 

 measured, the distinction between R. tigriyia and R. crassa would present 

 the same difficulties and fully justify the course I have followed, and 

 prove that, as in the European frogs, geographical non-isolation cannot 

 be appealed to as a safe criterion in deciding what warrants specific 

 rank. 



