18 ZOOLOGY. 
small, odd occipital, on each side of which, and immediately in advance of a large pair of post- 
occipitals, is seen a pair of small plates. Two more pairs, equal in size to the last, may be 
observed on either side of the large post-occipitals, and finally, behind the latter a series or two 
of quite small plates, limiting the occipital region. The nostrils open in one single plate; 
there are three lorals, one forming the continuation of the surciliary ridge, above which and the 
nasal, between these and the frontals, there are four minute, elongated plates irregularly dis- 
posed. The surciliary ridge is composed of six obliquely superposed laminz. The surocul- 
aries are nearly as large as the prefrontals, and surrounded by a series of small plates. The 
suborbital series consists of two plates only, a very long one beneath the orbit, and another 
rather small anteriorly, their inner crest or ridge being well marked. The posterior rim of the 
orbit is margined by small plates alike the temporal group. The surface of the lids is minutely 
granular; their margin is provided with a double series of very narrow, elongated, and very 
small plates. The rostral is transversally elongated, but quite low, or else narrow. The upper 
labials, five in number, are very narrow and elongated, increasing in length from the first to 
the fourth inclusive; the fifth is equal to the first. The supralabials are very exiguous; the 
middle ones being the longest. The symphyseal is larger than the rostral. The inferior labials, 
four in number, gradually lose their width posteriorly; the third is the longest; the fourth is 
the smallest of all. There are five pairs of mental shields, diminishing in size posteriorly ; the 
shields of the anterior pair being contiguous upon their inner margin. Between the inferior 
labials and the mentals a triple series of elongated scutelle or shields may be observed, one 
series only extending to the posterior half of the anterior inferior labial and anterior mental 
shield, The temporal shields are well.developed, slightly imbricated, rounded posteriorly, and 
carinated. The neck exhibits but a slight loose elevation of the skin, and is protected by acute 
and carinated scales, somewhat smaller than those of the back and sides. A small space imme-_ 
diately behind the ear is granular, though not as minutely as about the axille. 
The dorsal scales are large, subrhomboid, subacute posteriorly, and strongly carinated; they 
are smaller upon the neck, and diminish gradually in size towards the sides of the body and 
along the tail, where they constitute longitudinal series, instead of being arranged in verticiles 
or else concentrically. Upon the origin of tail their posterior margin is rounded and subacute; 
farther behind they gradually elongate, and the carina, instead of occupying the middle line of 
the scale, becomes oblique. Along the inferior surface of that organ they are more uniform 
and more slender. 
The limbs are very slender, and, when stretched alongside with the body, the anterior do not 
reach the setting on of the thighs, and the posterior the ear opening, in which respects, as in 
many others, this species may be distinguished from P. gracilis. The upper surface of these 
organs, from their origin to the tip of the fingers, is covered with carinated scales, similar in 
shape, though a little smaller than those of the sides of the back. They are plate-like on the 
upper surface of the fingers, and obsoletely carinated. On the palm of the hands and sole of 
the feet they are the smallest of all, except on the inferior surface of the arm and the anterior 
tibio-metatarsal region, where they approximate the granular aspect of the posterior surface of 
the thighs. ; 
The inferior surface of the head, neck, and abdomen, is covered with uniform scutelle, some- 
what smaller under the neck, and likewise diminishing in size towards the sides of the abdomen. 
The average size of these scutellx is smaller than the dorsal scales. Their posterior margin is 
rounded, and their surface slightly carinated from the chin to the preanal region, on the margin 
of which there are very small plates. The postanal region is granulated like the posterior sur- 
face of the thighs. 
The ground-color is uniform deep brown, with a reddish tint from the posterior third of the 
body to half the length of the tail. The sides bear two parallel light vitte, the uppermost 
extending from the occiput to the base of the tail, the other from the auditive aperture to the 
setting on of the hind legs. The inferior surface is unicolor, whitish or yellowish, with a me- 
