236 TROPICAL MEDICINE AND HYGIENE 



masseter muscle (fig. 101, mas., shows the line of cover). 

 In some cases the capsule has ligamentous attachments 

 to the quadrato-mandibular joint. Thus there is close 

 connection between the gland and the motor mechanism 

 of the jaw, so that when the snake bites' the gland is 

 compressed, the duct stretched, and the poison squeezed 

 along the duct. 



The duct (fig. 101, d.), enclosed in the same capsule 

 with the gland, runs below the eye, and immediately 

 beneath the skin of the upper lip, embedded in a mass 

 of upper labial glands. Just in front of the fang it is 

 recurved downwards to open on the anterior surface of 

 the fold of mucous membrane (fig. 94, s/z.) in which the 



FIG. 101. 



fang is ensheathed, in such a way that when the fang is 

 erected the opening of the duct is closely applied to the 

 corresponding opening in the fang. 



The fang (figs. 99, 100, 101) is an amplification of the 

 grooved tooth (fig. 98) of certain "suspicious" Colu- 

 brines. The open groove on the anterior surface of the 

 tooth has now become, by an infolding of its edges, a 

 canal with only the ends open. In some sea-snakes the 

 edges though much inflexed do not meet ; but in other 

 Thanatophidia they meet to form a tube, with one open- 

 ing near the base of the fang to which the orifice of the 

 poison-duct is applied, and another near the point of 

 the fang through which the poison is ejected. Except 



