gg HETERODON PLATIRHINOS. 



rostral plate, with a ridge on its upper surface continuous with that of the rostral 

 plate. 



The rostral plate is triangular, with its basis below and the apex very pointed 

 above, and recurved, with a strong carina or ridge on the upper surface. The 

 nasal plates are two on each side; the anterior is irregularly quadrilateral, 

 lunated on the posterior margin, with its anterior and inferior angle greatly 

 prolonged; the posterior is narrow, and concave in front to complete the nostril. 

 There are twelve orbital plates, the superior of which have been already 

 described; besides these, there are three anterior orbital plates, which are quadri- 

 lateral, the largest being above; the inferior orbital are five and the posterior 

 orbital three in number, all of which are quadrilateral. The upper jaw has eight 

 labial plates, quadrilateral, and increasing in size to the sixth, which is largest. 



The nostrils are very large, near the snout, and lateral. The eyes are large, 

 the pupil dark, the iris light grey. The neck is the size of the head when the 

 animal is quiet, but when roused or irritated it flattens it more than twice its 

 ordinary breadth. The body is elongated, thick, rounded above, but flattened 

 at the abdomen, covered with scales strongly carinated above, the three inferior 

 lateral rows being ecarinate, and with plates below. The tail is long, narrow, 

 and terminating in a point, with scales or bifid plates on its under surface. 



Colour. The head above is dusky, with a light band between the orbits; 

 behind the occiput is a dusky spot; a dark band begins at the back of each nostril, 

 which increases in size as it descends, and forms a large blotch on the side of the 

 neck. The body is iron-grey, or sometimes brownish-yellow, and marked with 

 a triple series of black or dark grey spots — those of the vertebral series being 

 sub-quadrate and elongated transversely; the spots of the lateral rows are rounded, 

 and many of them correspond with those of the vertebral line, while others alter- 

 nate with them. Sometimes the spots of the lateral and vertebral lines are 

 confluent, so as to give the appearance of bands. 



