310 MR. S. C. SAUKAR ON THE BUCCAL GLANDS 



considerably bent backwards. But apart from its being distin- 

 guished from the others by its size, it is important to notice that 

 it is separated from them by being enclosed in a special sac 

 (text-fig. 12, t.s.) formed from the folding of the mucous 

 membrane ; in fact, it has all the external appearance of a fang 

 contained in a tooth sac, and the similarity is so great that it can 

 readily be mistaken for the fang of the poisonous snakes. Further, 

 we can see from the portion of the longitudinal section of the 

 head of Tropidonotios that the tooth is specialised by the growth 

 of a cutting-edge on the posterior side. Besides, as in other 

 poisonous snakes, there are reserve teeth (r.t.) lying on the inner 

 side of this fang-like tooth. Text-fig. 11 shows the connection 

 of the duct of the parotid gland with tooth and mouth-cavity. It 



Text-fiffures 12 & 13. 



Fig. 12. — Tropidonotus stolaUis. Tooth sac and fang. t.s. tooth sac ; /. fang. 

 Fig. 13. — Tropidonotus stolatus. Longitudinal section of head in the region of 



the duct of the parotid gland, showing its opening into the buccal cavity. 



op.t.s. opening of duct into tooth sac ; op.d.p.g. opening of duct of parotid 



gland. X 63. 



is remarkable that the duct of this gland enlarges at first into a 

 special sac, the vestibule (-yes.), which is in communication with 

 the tooth sac by an opening {op.t.s.). The vestibule opens into 

 the buccal cavity (text-fig. 13, op.d.p.g.). Hence we see that 

 the duct, before opening into the buccal cavity, opens into the 

 vestibule, which becomes confluent with the lower part of the 

 tooth sac. By svich an arrangement it is made possible for the 

 snake to inject a part of the secretion from the parotid gland into 

 the severe wound at the time when it is being made by means of 

 the sharp cutting-edge of the tooth. 



Lycodon aulicus. 



Text-fig. 14 illustrates the general anatomy of the head dissected 

 from the right side. The general survey will show that it is 

 more advanced, and of a higher order than Tropidonotus in regard 



