918 MR. F. E. BEDDARD ON TWO SPECIES [Dec. 14, 



(5. Some Notes upon Boa occidentalis and Boa (PelopMlus) 

 Duulagascariensis. By Frank E. Beddard, M.A., 

 F.R.S., F.Z.S., Prosector to the Society. 



[Received October 26, 1909.] 

 (Text-figures 281-285.) 



In a series of papers recently communicated to this Society, to 

 which I shall refer in the course of the pi'esent communication, 

 I have dealt with a number of points in the anatomy of certain 

 snakes of the f.amily Boid?e belonging to the following species : — 

 Eunectes murbius, E. notceus, Boa constrictor, B. diviniloqua, 

 Eryx conictm, E. jaculus, E. johni, Gorallus coohii, C. madagas- 

 cariensis, C. canimts, Python sjnlotes, P. sebce, P. molurus, 

 P. regius, Enygrus carinatus. 



I have,recently had the opportunity of examining a specimen 

 apiece of the two species of Boa, B. occidentalis and B. madagas- 

 cariensis. The latter species has been referred to a genus 

 Pelophilas, and it is one of the species of Boa which occurs in 

 Madagascar. The distribution of this genus Boa is exactly 

 paralleled by the distribution of the allied genus Gorallus. 

 For in both the majority of the species ai-e Neotropical in range, 

 wdiile one or two are confined to the island of Madagascar. It is 

 therefore of particulai- interest to be able to compare the chai-ac- 

 teristics of the Madagascar Boa with those of its Neotropical 

 allies, and to set side by side the facts thus obtained with those 

 resulting from the anatomical study of the Madagascar and 

 Neoti'opical species of Gorallus. To some extent I am able, in 

 the present communication, to accomplish this comparison ; but 

 various reasons prevented me from being able to give so complete 

 an account of the facts as might be desired in the two species. 

 I can, however, direct attention to the more importaiit among 

 these. I shall deal with them in a comparative fashion, describing 

 the conditions of the lungs and certain blood-vessels in the two 

 species. 



§ Lungs. 



In Boa occidentalis the conditions of the two lungs differed 

 somewhat, as is the rule among these serpents. Not only are the 

 two lungs unequal in size, as is universal (?) among those Boidee 

 (the vast majority) which possess two lungs, but the Avindpipe 

 divides into two bronchi, which are unlike in the case of the 

 light and the left lung. In this species the bronchus of the 

 smaller lung pi'ojects but a short way into its interior as a 

 flattened plate ; its length was at most half an inch. At its 

 extremity the bronchus did not tail off into a seam running 

 along the lung substance such as occurs, as will be mentioned 

 presently, in the other lung. Its condition can be contrasted 



