3U 



MR. S. C. SARKAR OS THE BUCCAL GLANDS 



this that the aiTangeinent of the duct, vestibule, and tooth sac is 

 more oi' less like that of L^oodon, and this is emphasized in his 

 figure, which I reproduce. 



Oxyhelis, therefore, seems to be one of those types which 

 connect the Aglypha with the Opisthoglypha. On the one hand 

 it retains the aglyphous condition of the duct opening into the 

 mouth, and on the other it has the characteristically opisthogly- 

 phous grooved teeth. 



Ohrysopelea ornata. 



The general description of the glands and teeth has been given 

 before (p. 304), but for comparison and discussion we will 

 mention some of the facts again. On compai-ing the external 

 appeai-ance of the poison gland of Chrysopelea (text-fig. 17) 

 with that of Oxyhelis, described by West, and also with that 

 of Lycodon, one is struck with the relative reduction in size ; in 

 fact, the gland is restricted to a very small area, and in shape and 

 size resembles that of Dendrophis, which stands lowest in my 

 series in the Aglypha (p. 307). In other words, it seems to be 

 a case of retrogressive rather than of progressive evolution. But, 



Text-figure 17. 

 ^9 Hg 



Ghryso'pelea ornata. Dissection of head from the left side. S.g. Harderian 

 gland; i.l.g. inferior labial gland; p.g. parotid gland; s.l.g. superior labial 

 X3. 



on the other hand, it must be remembered that the snake has 

 acquired more perfection by developing a deeper groove, by 

 means of which it is confident of injecting a sufficient quantity of 

 the poison into the wound, and that therefore it is obviously 

 unnecessary to have a large gland and huge amount of secretion. 



It also will be seen that the secretion coming from the gland 

 passes directly into the tooth sac, where greater use can be made 

 of it than if it were squandered in the buccal cavity. 



Now, if we examine the transverse section of Chrysopelea (text- 

 fig. 18) and compare it with that of Oxybelis (text-fig. 16), we 

 find the former specimen is more advanced in many ways. The 

 fang has lost the remains of the cutting- edges on both sides, but 

 has developed a deeper groove than that in the fang of Oxyhelis. 



