68 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. 
Cotour. 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. 
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