_Corpore gracili: capitis squamis lævibus, non imbricatis: aurium
margine anteriore minutè bi-tridentato: collo vix plicato, squamis
imbricatis: serie unicâ squamarun supralabialium: femorum facie
posteriore omninò granulosâ._
Habitat, Port Desire, Patagonia. Mr. Darwin, MS.
DESCRIPTION.—This new species is more slender and graceful in its
general form than any other of the genus, not excepting _Pr.
tenuis_, which in its general proportions it considerably
resembles. The head is rather short, the anterior portion
including the eyes being nearly an equilateral triangle. The
muzzle is rounded. The scales of the head flat, rather large,
consisting behind the nose of three series of 2, 3, 3, and 2,
mostly hexagons. The nostrils are small and perfectly round, the
superciliary ridge is very slightly marked; there is but a single
row of small linear scales between the labial and suborbitar. The
ear is of moderate size, the anterior margin having two or three
small projecting scales. The scales on the temples are imbricated
and smooth; those of the sides of the neck also imbricated but
very small. The neck is almost wholly without a fold, having
merely a slight loose elevation of the skin. The scales of the
back are small, rhomboidal, flat, the carina low, and not pointed
at the extremity. They consist of about ten rows on each side of
the median line. Those of the sides and belly are wholly without
any notch on the free margin. The scales around the axillæ, and
those of the posterior face of the thighs are granular. The tail
is of considerable length, being more than twice the length of the
head and body. The limbs are remarkably long; the anterior, when
pressed against the side, reaching to the setting on of the thigh,
and the posterior reaching forwards nearly to the ear. The general
colour of the upper parts is greyish brown, with a yellow
longitudinal fascia extending on each side from the upper edge of
the orbit to some distance along the tail—and another from beneath
the eye to the thigh. The middle of the back is lighter than the
sides—beneath the second lateral line the colour fades, and on the
belly it is pale buff or light yellow. The sides are dotted with
black; and there are some dark waved lines and dots beneath the
lower jaw.
This species is at once distinguished from every other by the fold
of the neck being scarcely cognizable. It is however not so
absolutely wanting as in _Pr. Chilensis_.
DIMENSIONS.
Inches. Lines.
Length of the head 0 5
of the body 1 4
of the tail 3 8
────────────────────────────────────────────
Total length 5 7
Length of anterior extremity 0 7
of posterior extremity 1 1
A single individual of this species was taken by Mr. Darwin at Port
Desire.
_Plate 1._
[Illustration:
_Drawn from Nature by B. Waterhouse Hawkins, on stone in Lithotint C.
Hullmandel’s Patent._
]
_1. Proctotretus Chilensis_ _Nat. Size._
_2. ____ gracilis_ „
────────────────────────────────────────
_1a._ _1b._ _Magnified
views._
_2a._ „
_Plate 2._
[Illustration:
_Drawn from Nature by B. Waterhouse Hawkins,
on stone in Lithotint C. Hullmandel’s Patent._
]
_1. 2. Proctotretus pictus._ _Nat. Size._