REPTILES. 17 
being dark brown. The first series stretches immediately along the inner margin of the upper 
vitta; the second is enclosed between the two vitte. The lower half of the flanks, beneath 
the inferior vitta, is covered with irregularly vertical or rounded black spots. The inferior sur- 
face of the body is unicolor whitish or greyish; numerous interrupted series of linear spots are 
observed under the head and inferior portion of its sides, The vittee upon the latter regions 
are margined with black. There is an irregular black spot at the shoulder close to the inser- 
tion of the fore limbs. The series of dorsal spots extends along the upper surface and sides of 
the tail; the latter is maculated with greyish below. The limbs above are transversally barred, 
and beneath they are of the same hue as the abdomen. 
In some, probably male specimens, the vittee and spots are less distinct, and immerge into 
the ground-color. The sides of the abdomen are of a reddish metallic hue, with black and 
bluish small spots. 
Specimens of this species were collected in the vicinity of Santiago, Chile. 
Plate XXXVIII, fig. 5, represents the profile of Proctotretus femoratus, size of life. 
fig. 6, is the head, seen from above. 
fig. 7, a side view of the head. 
fig. 8, the head, from below. 
fig. 9, shows the inferior surface of the anterior limb. 
fig. 10, the inferior surface of the posterior limb and the vent also. 
fig. 11, some dorsal scales. 
fig. 12, some abdominal scutelle. 
Figs. 6—12 are slightly magnified, in order to show readily the structures they are intended 
to represent. 
PROCTOTRETUS STANTONTI, Girard. 
Prare XU, Figs. 13—20. 
Spec. cHAR. Cephalic plates rugose. Auricular aperture moderate, margined anteriorly 
with very small scales, one of which is larger than the rest. One series of supralabials. Tem- 
poral shields well developed, subrounded, imbricated, and carinated, Sides of neck with one 
indistinct fold, and covered with acute and carinated scales, a little smaller than those of the 
back, which are large, posteriorly subacute, and strongly carinated. Abdominal scutellee 
rounded posteriorly and slightly carinated. Posterior surface of thighs granular. Tail elon- 
gated and slender. Ground-color deep brown, with a reddish tint posteriorly ; two parallel 
vittze on the sides. Abdomen unicolor, with metallic reflections. 
Syy. Proctotretus stantoni, Grp. Proc. Acad. Nat. Se. Philad. VII, 1854, 227. 
Descr. The specimen figured—the only one in our possession—is of a rather small size, and, 
in all likelihood, not fully grown. It resembles, in general appearance, P. gracilis, particu- 
larly in its system of coloration, differing, however, in too many peculiarities of structure to 
dwell at all upon that external resemblance. 
The head is very depressed and sloping upon the frontal distance. Seen from above, its 
shape is subovoid, rather narrow anteriorly. The cephalic plates, the surface of which is 
slightly rugose, are well developed, and the frontals symmetrically arranged; thus we find 
two pairs of small prefrontals and three pairs of considerably larger postfrontals, separated by 
a transverse series of three plates, the middle one of which is much larger than the adjoining 
two, though itself equal to the smallest postfrontals. There is a vertical of medium size, a 
