ANB TEETH OF THE OPISTHOGLYPHA. 313 



diagrams. So I have to base my arguments on West's account 

 in the Proceedings of the Zoological Society, 1895, According to 

 West, " the poison gland is very clearly defined and the superior 

 labial gland is exceedingly long and narrow ; it reaches to the 

 anterior extremity of the maxilla, and consists of much smaller 

 lobules than the poison gland. . , The maxilla possesses more 

 teeth than that of any other snakes examined, there being twenty 

 in one uninterrupted series. The first seventeen are equal in size 

 and much curved ; the posterior three are a little larger, com- 

 pressed laterally, and the external face of each possesses a very 

 shallow groove. The muscular folds surrounding these three 

 posterior teeth are not united in front, and in consequence of a 

 thin muscular fold across the base of the anterior grooved tooth 

 the poison duct in this snake is placed in communication with the 

 interior of the mouth before it is with the groove of the tooth." 

 (See text-fig. 16.) 



Text-figure 16. 



.d. 



■P-3- 



op.dp.j. 



Oxyhelis fulgida. Transverse section of head in the region of the fang and the 

 duct of the poison gland opening into the mouth (after West), d.p.g. 

 duct of poison or parotid gland ; f. fang ; g. groove ; op.d.'p.g. opening of 

 the duct of the parotid gland j t.s, tooth sac. 



West has not given any figure of the dissection of the head, nor 

 any section of the tooth (fang), but from the above description we 

 may surmise from his use of the words '* very clearly " that the 

 parotid gland is even more highly difi"erentiated in Oxyhelis than 

 in L-i/codon. With I'egard to the fang, we may safely conclude 

 from the above account of its lateral compression that it still 

 retains some indication of cutting-edges on both sides like those 

 of Lycodon, and at the same time has developed in " the external 

 face ... a very shallow groove." Referring now to the tooth- 

 sac and the duct, I think that the thin muscular fold which West 

 describes is the wall of what I have called the vestibule. Text- 

 fig. 16 shows its connection with the buccal cavity, and probably 

 if another series of sections were examined we should find the 

 openings of the vestibule into the tooth sac. We can infer from 



