The proportions of the limbs vary in the two sexes. In the male they are considerably longer than in the female. In the latter the posterior extremity when placed against the side extends only to the arm, in the former it reaches to the ear. The ground colour of the back is chesnut brown or greenish brown, with a bright metallic green glance in certain lights; there are two light buff longitudinal fasciæ running the whole length of the body; the under parts are of a bright metallic blue colour. Mr. Darwin states that in one specimen there were emerald spots on the sides, which did not exist in another individual. This may possibly be a sexual peculiarity.

DIMENSIONS OF A MALE SPECIMEN.

Found by Mr. Darwin at Valparaiso, and at Valdivia; the former is a very dry rocky country, with a scanty vegetation; whereas the latter is nearly level, covered with the thickest forest, and the climate exceedingly humid.

Proctotretus Kingii, N.S.

Squamis capitis neque imbricatis nec carinatis; supralabialibus in serie unicâ; aurium margine anteriore granuloso; interdum unidentata; squamis, dorsalibus carinatis, posticè acuminatis, femorum facie posteriore præcipuè granulosâ, sed portione parvâ, caudam versus, squamis parvis, rotundatis imbicratis tectâ.

Habitat, Port Desire in Patagonia.

Description.—General form robust and full; the head short, thick, and passing into the neck without any distinct contraction; the muzzle rounded. Scales of the head larger in proportion than in Pr. Fitzingerii. Ear large, oval, with the anterior margin granular, sometimes slightly toothed. Scales of the temples of moderate size, imbricated, smooth, somewhat raised. A single range of oval moderate-sized scales between the labial and the orbital scales on the sides of the neck, above and behind the shoulder small, granular, and some of them having a minute pore. Scales of the back of moderate size, larger than in Fitzingerii, rhomboid, having a rather prominent carina, and terminating in a distinct point. Scales of the under parts smooth and rhomboidal. The posterior surface of the thighs is for the most part granular, but a small portion near the groin is covered with larger imbricated scales; to a much smaller extent, however, than in Fitzingerii, and other species which possess this character.

The general colour of the upper part of this species is a rich dark brown, with whitish transverse bands and spots, having a black margin. I have figured in fig. 2, of Plate VI., a remarkable variety in which the bands are alternate black and white, and a broader and a narrower longitudinal fascia of a yellowish-white colour, run the whole length of the body on each side. The under parts are yellowish-white, with dark or almost black spots; under the throat bluish-gray with white spots.

This species much resembles Pr. Fitzingerii in many of its characters, as well as in its size. It may, however, be at once distinguished from it by the character of the scales of the back, which in this species are very distinctly carinated, of a rather elongated form, and pointed at the extremity; whereas in the other they are shorter, smaller, the carina is very slight, almost indistinct, and the posterior extremity is obtuse.

The tail in the larger figure of our plate is deformed, having been renewed. The specimen figured at (2,) in the same plate, is so remarkably distinct in the colours and marking, as to lead me to suppose that it may possibly be a different species.

Proctotretus Darwinii.

Corpore subdepresso; capite squamis numerosis, parvis, subelevatis, lævibus non imbricatis; aurium margine anteriore integro; temporibus colloque granulatis; serie unicâ squamarum supralabialium; facie posteriore femorun partìm granulosâ, partìm squamis imbricatis tectâ.

Habitat, Bahia Blanca, Northern Patagonia. Mr. Darwin.