16 ZOOLOGY. 
very low. The upper labials are elongated and narrow, six in number, increasing in size from 
the first to the fourth, which is the longest, then diminishing again posteriorly. The supra- 
labial series is composed of about an equal number of similar plates but narrower still. The 
symphyseal is larger than the rostral, and especially broader upon its middle region. The 
inferior labials, six or seven in number, are broader than the upper, diminishing gradually 
backwards. There are four pairs of mental shields; the anterior pair is the largest, con- 
tiguous upon the inner margins, whilst the other pairs diverge in diminishing in size pos- 
teriorly. A series of infra-labials may be traced from the angle of the mouth to between a 
portion of the first inferior labial plate and anterior mental shield. The temporal plates are 
well developed, particularly towards the upper region; they are posteriorly obtuse, imbricated, 
and distinctly carinated. The side of the neck, which exhibits a very obsolete fold, is covered 
with small, acute, and carinated scales. The posterior margin of the auricular aperture and 
region of the shoulder are minutely granular. The dorsal scales are rather large upon the 
back, diminishing in size towards the middle of the flank, being carinated and acute posteriorly. 
The inferior half of the flanks are covered with scales or scutellz similar to those which exist 
upon the belly, being only a little smaller and obsoletely carinated upwards. The abdominal 
scutelle or scales are smooth, obtuse posteriorly, and rather smaller than the dorsal scales. 
Under the head and throat they do not differ materially from those on the abdomen, but are a 
little larger under the head than under the throat: their posterior margin is entire. If an 
obsolete notch is to be observed at all, it is in those occupying the flanks, but that notch may 
be owing to the fact that the carinz do not always extend to the posterior margin. The upper 
surface of the anterior limbs is covered with scales similar to, but smaller than those on the 
back, obtuse and smooth upon the anterior region and the carpus. Under the forearm they are 
very small and smooth, increasing in size under the arm, and again diminishing towards the 
palm of the hand, which is entirely covered with them, and not only carinated and posteriorly 
acerated, but provided also with a lateral acute processus, particularly developed upon the meta- 
carpal region. The fingers above are plated and smooth; beneath they are provided with small 
scales, carinated, acerated posteriorly and disposed upon regular transverse rows. The fingers 
have the same relative length, and the nails the same form as in P. tenuis. The hind limbs 
and the tarsi are covered above with scales similar, but smaller than those on the back, and 
larger than on the fore limbs, carinated even on the tarsi. The anterior tibio-metatarsal region 
is distinguished by very small scales, almost passing to the granular aspect. The posterior 
surface of the thighs is granular; whilst their inferior surface is covered anteriorly with scutel- 
lx similar to those of the abdomen, and posteriorly with three or four series of scales, some- 
what acute and projecting beyond the surface of that organ, the external series being the most 
developed. On the inferior surface of the femoral region the scutellz or scales are subcarinated 
and well developed, the external series projecting a little beyond the surface of the organ. On 
the sole of the feet the scales are quite small, acute, and more distinctly carinated. The toes 
are surrounded with small subverticillated scales, more uniform and more distinctly carinated 
beneath than above. The proportional length of the toes and the form of the nails is the same 
as in P. tenwis. The caudal scales have likewise the same general structure; there being, 
however, no contrast in size between them and those of the back, though a little larger on the 
base of that organ. The ground-color is brown, olivaceous, or blackish. The upper surface of 
the head is either unicolor or dotted with blackish; its sides generally exhibit two or three 
oblique and black lines extending from beneath the orbit towards either the margin or the 
angle of the mouth. The suborbital ridge may be black also. There are two parallel light 
vitte on the sides of the body, the uppermost extending from the surciliary ridge to a portion 
of the tail; the lower one extends from the temporal region across the upper edge of the auricu- 
lar aperture, and above the insertion of fore limbs to the groin. The dorsal region sometimes 
is lighter than the sides, and appears like another broad vitta. There are two series of 
black, transversally elongated spots, with a light or bluish margin; the intermediate space 
