AND TEETH OF THE OPISTHOGLYPHA. 



305 



The Harderian gland consists of three lobes; two portions lie 

 within the orbit and one outside. 



Genus Tarbophis. 

 Tarbophis variegatus. 



The specimen of this snake was in a damaged condition. 



The poison gland is large, and quite distinct from the superior 

 labial gland ; it is spindle-shaped, the anterior end lying below 

 the middle of the eye. The superior labial gland is narrow, and 

 reaches the anterior end of the maxilla, where it enlarges and 

 curves round to join the gland of the other side. It is also 

 continuous below the poison gland. The inferior labial gland 

 extends from the very end of the mandible in front, and meets 



Text-figure 7. 

 P-9- 



Tarbophis variegatus. Dissection of head from the right side. /. fanp 

 inferior labial gland ; p.g. parotid gland; s.l.g. superior labial gland. 



X3. 



the superior labial gland posteriorly behind the angle of the jaw. 

 Of the nine teeth in the maxilla the last is large and grooved, 

 and the rest are smaller and subequal in size. The grooved 

 tooth is situated far behind within the buccal cavity. The 

 groove is placed on the external surface of the tooth, and does 

 not extend up to the end of the tip. There are about fourteen 

 teeth in the mandible, the series decreasing in size posteriorly. 

 They are alternately hinged and fixed. The Harderian gland 

 consists of two lobes, one outside and the other within the orbit, 

 and it is perforated by the optic nerve. 



Genus Psammophis. 



PSAMMOPHIS SIBILANS. (Text-fig. 21.) 



The poison gland of this specimen shows the most highly- 

 developed condition among the opisthoglyphous snakes that_ I 

 have examined ; it is a distinct organ, and has assumed a definite 

 shape, being oval. It is comparatively very large. The lobules 

 of the gland are much smaller than those of the superior labial 



