AND TEETH OF THE OPISTHOGLYPHA. 303 



extension to the moutli and placing the fangs in a more exposed 

 position. There are eighteen maxillary teetii ; the last two are 

 grooved and large. The grooved teeth are placed slightly- 

 further forward away from the angle of the jaw. The hinder 

 grooved tooth is hinged. The groove is situated on the anterior 

 side of the tooth at its proximal end, while on the outer side at 

 the distal end. The groove does not extend up to the very end 



Text-figure 5. 



Cerberus rhyncJiops. Dissection of head from the right side. /. fang ; i.l.g. 

 inferior labial gland ; p.ff. parotid gland ; s.l.g. superior labial gland. X 3. 



of the tooth, it is deep and almost takes the shape of a canal. 

 The mandible contains twenty-two teeth of unequal size. 



The Harderian gland is a little peculiar, for the greater part 

 of the outer portion lies under the poison gland. There are 

 three lobes ; the external part is cylindrical, tapering at the 

 posterior end, while the other two within the orbit divide into 

 dorsal and ventral portions surrounding the optic nerve. 



Genus DiPSAS. 



DiPSAS TRIGONATA. 



The poison gland is clearly distinguishable from the superior 

 labial gland, and anteriorly extends up to about the middle of 

 the eye. The lobules of this gland are smaller than those of the 

 superior labial gland and more distinct. The latter extends to 

 the very end of the mouth anteriorly, and ends posteriorly about 

 the angle of the jaw. It is continuous all along. The inferior 

 labial gland is more highly developed than the superior labial 

 gland, extending far back so that it almost meets the superior 

 labial gland behind the angle of the jaw. The maxilla con- 

 tains twelve teeth ; the last two are grooved. The teeth are 

 larger in front except the first one. The poison fangs are bent 

 considerably backwards and slightly inwards so that the pointed 

 ends are directed towards the pharynx. At the proximal end 

 the grooves of the teeth lie on the outer side, while at the distal 

 end they are in front of it, The grooves extend three-fourths 



