146 MR. F. E. BEDDARD ON THE ANATOMY [Mar. 3, 



quoted in other papers comnnmicated to the Society facts from 

 my dissections relative to the shortness of this vein in both of 

 those two great divisions of the Oj)hidia. With regard to the 

 Colubrine Serpents I have now two other examples to mention 

 Avhich bear out the view expressed above. In Jlelicops angtdatus 

 the azygos is smaller than in any snake in which I have seen it. 

 A stoutish vein on the right side connects the parietes with the 

 precaval, and nothing further is seen of it after the point at which 

 it emerges from the parietes ; it is not at all continued down the 

 body In Heterodon nasicus the azygos is also small, but not 

 smaller than in some other Colubrines in which I have de- 

 scribed it. The vein, which is, as usual, on the right side of the 

 body, is formed by the confluence in regular order of four inter- 

 costal branches. The last of these emerges from a circular orifice 

 in the parietes with well-marked edges of very much greater 

 diameter than the vein which it permits to pass out. In the 

 case of the other branches no such orifice was visible ; they 

 simply push their way between the various layers of tissue. 

 In the Bold* on the whole the azygos is better developed than 

 in the non-Boine snakes, but in no Boid which I have had the 

 opportunity of studying is that vein so continuous for so many 

 segments as in Corcdlus cookii. I only observed this in one 

 specimen which happened to be particularly favourable for this 

 examination. Furthermore, the arrangement was the same on 

 both sides of the body, and the appearance presented by these 

 veins was therefore reminiscent of the postcardinals in the 

 Tailed Amphibians as figured by Hochstetter *, and as I have 

 m.yselft observed. I believe that there are no embryological 

 data as to the significance of these veins in the Boidas, and I 

 thei'efore use the term "azygos" as being in the present state of 

 knowledge a somewhat vague term J with nevertheless a definite 

 meaning of a kind §, but one which implies no homologies with 

 other vertebrates. As I have no facts about the same veins in 

 Corcdlus madagascariensis, and as our knowledge of this vein 

 in the Ophidia generally is not extensive, I can make no com- 

 parisons of value except, indeed, to point out that Corcdhis is, on 

 the whole, like other Boidse in this respect. 



§ Liver. 



Corcdlus madagascariensis showed a curious peculiarity in the 

 structure of the liver. The posterior end of one of the lobes of 

 that organ was enormously prolonged as a thin tail of hepatic 

 substance. This state of aflairs is merely an exaggeration of the 

 commonly found projection of the one of the two liver -lobes 

 posteriorly beyond the other. In Corcdlus cookii there is some 



* Morph- Jahvb., Bd. xiii. 1888, p. 119. 

 f In Amhli/stoma tenebrosum. 



X There is not ahvaj's a strict homology, as I believe, even Ijetween veins in 

 different mammals wl\ich have been described under this name. 

 § J. e., a vein which draws blood from the dorsal thoracic parietes. 



