Reptiles of Massachusetts. 35 
and elongated at the tip; it is covered with scales 
on the posterior part, and with plates on the anterior 
and on the vertex. The vertical plate is regularly 
pentagonal, with its broadest point directed forwards. 
The superior orbital are quadilateral, elongated, and 
broadest posteriorly, with their outer margins pro- 
jecting over the eye, which gives a sinister look to 
the animal. The occipital plates are rhomboidal. 
The frontal are quadrilateral, with their anterior in- 
ferior angles very much prolonged ; the anterior fron- 
tal are triangular, with their bases directed inwards, — . 
and their apices rounded, and turned to the nostrils. 
Between these frontals, so as to prevent them coming 
in contact with each other, is a narrow elongated 
azygos plate, reaching from the posterior frontal to 
the 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 nostril 
plates are two on each side; the anterior quadri- 
lateral, lunated on the posterior margin, with its an- 
terior and inferior angle greatly prolonged; the pos- 
terior 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 quadrilateral, 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 six lateral plates, quadrilateral, 
and increasing in size to the sixth, which is largest. 
