SHIELDS 



223 



On the side of the head (fig. 93) we distinguish the 

 rostral (r.) covering the tip of the snout; the upper 

 labials (s./.) covering the upper lip, and the lower 

 labials (LI.) covering the lower lip ; the nasal (n.) pierced 

 by the nostril ; the preoculars (pr.o.) in front of the eye, 

 and the post-oculars (p.o.) behind it ; and the temporals 

 (t.t.) behind the post-oculars. Between the nasal and 

 pre-ocular in all but a few harmless Colubrines, and quite 



FiG. 94. 



exceptionally in poisonous Colubrines, lies a loreal shield. 

 Importance has often been attached to the presence or 

 absence of the loreal shield as a supposed index of the 

 nature of the snake whether poisonous or otherwise. 

 It is an uncertain index even for Colubrines, and is 

 not at all applicable to Viperines, of which latter all are 

 poisonous and many possess a loreal shield. The upper 

 labials commonly touch the eye, but sometimes there are 

 some small intervening suboculars. 



On the under side of the head (fig. 94) the shields 

 bearing special names are the lower labials (/./.); the 

 mental (m.) in the middle line of the mouth and chin, 



