136 MR. F, E. BEDDARD OX THE A^UTOMy [Mar. 3, 



my observations by the dissection of so many examples allows 

 perhaps of a more reliable comparison of the two species, though 

 it must be remembered that I only dissected one example of 

 Cor alius madagascarie i is is . 



The seven examples of Corallus cookii which I have dissected 

 were of different sizes and show among themselves a certain 

 amount of variability in structure which will be dealt with in 

 the following pages. For the convenience of reference, in the 

 course of my remarks I shall refer to them as Specimen A, B, &c. 

 Their lengths were as follows (the lengths given, it should be 

 observed, are of the body proper, that is to the cloacal aperture. 

 I did not trouble to measure the tail) : — 



A. 2 64 inches. B. J 63 inches. C. cJ 48| inches. D. c? 

 71 inches. E, c? 65 inches. F. 64 inches. G, 53 inches. 



Of the last two examples I did not ascei'tain the sex, I shall 

 now deal with certain organs and systems seriatim. 



§ Externcd Characters. 



In distinguishing the various species of Corallus the one from 

 the other in his Catalogue, Mr. Boulenger makes use of a large 

 number of characters, but does not avail himself of tlie number 

 of scales which border the mental gi-oove. This chai'acter happens 

 to be of some use in the determination of the two species wdth 

 which I deal in the present communication. I ought to say, 

 first of all, that a faint doubt hangs over the identification of 

 specimen A. In this individual I did not ascertain definitely 

 that it belonged to the species Corallus cookii by counting the 

 number of scales in the rows upon the body. I do not think, 

 however, that there is really much danger of a mistake having 

 been made in its identification ; for in every other character 

 which I examined it agi'eed broadly with the other individuals 

 in which I did carefully count these scales. The numbers quite 

 agreed with the figures given in his Catalogue by Mr, Boulenger. 

 As to the scales which border the mental gi-oove, I found in 

 Corallus madagascariensis that the number on each side was 

 eight. In Corallus cookii there are not less than nine and not 

 more than eleven of these scales on each side, the prevailing 

 number being ten. There is thus a difference, though doubtless 

 a slight one, between the two species. The greater length of the 

 mental groove in Corallus cookii gets pei'haps some additional 

 significance as a character of value from the fact that there is 

 precisely the same difference, as I have already recorded*, 

 between the two species of Anaconda, viz., Eunectes murinus 

 and E. nota^us. In the former there are seven scales on each 

 side and in the latter only five. The same kind of difference 

 also distinguishes two species of the genus Boa ; for in one 

 individual of Boa diviniloqua (a male) the mental gi'oove was 

 very short indeed and bordei-ed only by two scales on either side, 



* P. Z. S. 1906, p. 15. 



