306 MR, S. C. SAKKAR ON THE BUCCAL GLANDS 



gland. The latter is continuous below the poison gland, and 

 extends anteriorly to the very end of the snout, meeting its 

 fellow of the otlier side. Behind it extends further back than 

 the poison gland. The -inferior labial gland is also well developed, 

 and has the appearance of a compact body reaching as far as the 

 end of the mandible, and posteriorly it meets the superior labial 

 gland behind the angle of the jaw. The maxilla possesses four 

 medium-sized teeth in front, then two large, solid fang-like teeth, 

 followed by a series of four small equal teeth and finally two large 

 straight fangs. The groove of the posterior maxillary teeth is 

 placed on the anterior face of the tooth, and extends throughout 

 the length of it, ending at the tip. The teeth in the maxilla and 

 the mandible are straight and slightly directed backwards, and 

 tliey also show an alternating arrangement of hinged and fixed 

 teeth. The Harderian gland consists of two lobes, one outside 

 and the other within the orbit. The latter shows a superficial 

 division into two. 



Discussion on the Evolution of the Opisthoglypha. 



It is generally admitted that the opisthoglyphous snakes are 

 evolved from the Glauconiidfe, and that the immediate ancestors 

 of the Opisthoglypha are the Colubridfe Aglypha. Boulenger 

 pointed out in the year 1896 (1) "that from Aglj^phodont 

 forms, in which the teeth increase in size posteriorly, we are 

 gradually led to the Opisthoglypha, which are only to be distin- 

 guished by the presence of more or less deep grooves on the 

 posterior fang-like teeth," 



As far as xaj own observations go, I find that, apart fi-om the 

 gradual increase in the size of the teeth, there is a change 

 concurrently in the structure of the particular tooth which is 

 situated in the posterior portion of the maxilla near the opening 

 of the duct of the parotid gland into the mouth. At the same 

 time, the parotid gland itself undergoes a gradual transformation 

 from a sim]>le structure, distinguishable only from the superior 

 labial gland by its colour, to a separate distinct organ lying 

 detached from it. There also occurs a change in the connection 

 of the duct of the parotid gland with the buccal cavity and the 

 teeth. 



My observations are based on a study of the following types, 

 arranged iu order: — 



Dendrophis pictus. "1 



Tropidonotus stolaiios. V Aglypha. 

 Lycodon aulicus, J 



Oxyhelis fulgida. "^ 



Ghrijsopelea ornata. Upisthoglypl: 



Dryophis mycterizans. \ ^ 



lia 



Psanimophis sibilans. J 



