18 
ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 
of the Geckos. Its habits are singular. It lives on the dry sand of the beach, 
at some distance from the vegetation, and the colour of the body much resembles 
that of the sand. When frightened it depresses its body, stretches out its 
legs, and closing its eyes tries to escape detection. If pursued it buries itself 
with great quickness in the sand ; but as its legs are short, it cannot run very 
swiftly.” 
Proctotretus pectinatus. 
Plate IX. — Fig. 2. 
Capite squamis subcEqualibus, rhomboideis, imhricatis, carmatis tecto. 
Proctotretus pectinatus, Bibr. Hist. Rept. IV. p. 292. 
Habitat, Patagonia. 
Description. — The scales of the head are narrow, closely imbricated, strongly but not acutely 
carinated, and the anterior ones arranged in somewhat of a radiating direction from the muzzle. 
There is but a single series of scales between those of the upper lip and the orbit, and these, 
together with all the scales about the head, partake of the carinated and elongated character 
already described. A single strong triangular scale and two smaller ones are placed on the 
anterior margin of the ear, which is narrow, oval and reniform. The scales of the temples and 
sides of the neck are rhomboidal, acute, carinated and imbricated. There is a longitudinal 
fold on each side of the neck and a transverse one anterior to the shoulder, behind which is a 
deep depression. The scales of the back and side are prominently and acutely carinated, those 
of the central line being rather more prominent than the others ; and above this there is on 
each side a marked longitudinal lateral crest extending from beneath the eyes to the base of 
the tail. The scales constituting these crests are very prominent, narrow and acutely'^ carinated. 
The scales of the belly are also imbricated and rhomboidal, but flat; those of the under surface 
of the hands and feet are carinated ; and those of the toes have thi’ee carinae. The body is 
somewhat depressed as is the tail at its commencement, becoming more rounded and rather 
abruptly smaller at some distance from its origin. The fore-foot reaches to about two-thirds of 
the distance from the shoulder to the side, and the hinder extremity thus placed extends to the 
shoulder. 
The colours of this most elegant of all the species of the genus are very beautiful. “ This 
is the most beautiful lizard,” says Mr. Darwin, “ I have ever seen ; the back has three rows of 
regular oblong marks of a rich brown, the other scales symmetrically coloured either ash or 
light brown; many of them of a bright emerald green; beneath pearly, with semilunar spots of 
brilliant orange on the throat.” I find in the specimens I have examined that the pectinated 
lateral crests are white, and the brown oblong marks of the back are bordered with a similar 
colour. There are always three white transverse lines across the head. 
