AND TEETH OF THE OPISTHOGLYPHA. 



321 



Text-fisrure 27. 



max. ^ ^ *-^- 



6. Chrysopelea ornata. 



The poison gland is reduced in size, due to the fact that the fang (/) has acquired 

 a deeper groove (g), through which a greater amount of secretion can be 

 injected into the wound, and there is very little waste. The wall between 

 the vestibule (ves.) and the tooth sac has disappeared; at the same time 

 the opening of the duct into the mouth cavity is closed, and hence the 

 duct i^p.g-) opens directly into the tooth sac. 



Text-figure 28. 



duct.p.g. 



7. Dryophis mycterizans. 



The poison gland (^.^.) is much more differentiated. The groove [g.) of the fang is 

 deeper and almost like a canal. The duct {duct p.g.) has shifted upward to 

 open into the tooth sac almost near to the base of the fang, which has also 

 moved forward in the mouth cavity. 



Text-figure 29. 



ductp.g. 



8. Fsammojphis sibilans. 



The poison gland {p.g.) is distinct— almost a separate organ. The fang (/) is 

 almost straight, and has shifted still further in the mouth cavity. The 

 groove lies in front of the tooth instead of on the side, nearer to the beginning 

 of the groove. 



