16 
ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 
minuih granulato. Seriehus duabas squamarum supralabialium. Femorum facie 
posteriore parthn granulosa, partim squamis minutis mibricatis tecta. 
Proctotretus Weigmannii, Bibr. 1. c. p. 284. 
Habitat, Northern Patagonia and La Plata. 
Description. — Head rather short, covered with numerous slightly raised scales, not carinated nor 
imbricated ; snout rather obtuse and slightly rounded, nostrils semicircular. Two series of 
very small scales between the labial scales and the orbit. Ear of moderate size, the anterior 
margin furnished merely with minute granular scales. Scales of the temples flat and smooth. 
Fold on the sides of the neck distinctly marked, anteriorly bifurcated; the remainder some- 
what waved. Sides of the neck granulated scales of the whole of the upper and back parts 
of the body and tail of moderate size, the carina little elevated and the point but slightly 
prominent. The scales of the inferior parts of the neck and body are smooth, polished, and 
imbricated, those towards the sides of the neck minutely emarginated. The scales of the 
limbs resemble those of the body ; those of the upper surface being carinated and those 
beneath smooth. The posterior face of the thighs is generally covered with granular scales, 
but there is on this part near the tail, a distinct patch of imbricated scales resembling those 
of the inferior surface of the thighs, a character by which this species may at once be 
distinguished from all others. The anterior extremity placed against the side reaches about 
two-thirds of the distance towards the groin ; the posterior extremity reaches forward to the 
shoulder. 
Colour. — The back and sides are brownish gray, with a yellow longitudinal band on each side of 
the back, separating transverse black or dark brown bands of various size and form ; and there 
is in most on each side a smaller interrupted yellow band. The under parts generally of a 
yellowish white, in some individuals sparsely dotted with black. Mr. Darwin says of some 
individuals of this species that they have “ an orange-coloured gorge, and faint stripes of blue,” 
also “ ash-grey with dark brown marks and specks of orange and blue.” 
DIMENSIONS. 
Inches. Lines. 
Length of the head 0 5 
of the body 1 5 
of the tail 2 2 
Total length .... 4 2 
Length of anterior extremity 1 1 
of posterior extremity 0 8 
This species was found by Mr. Darwin at Bahia Blanca and at Rio Negro, 
on the northern confines of Patagonia, and at Maldonado, near the mouth of the 
Rio Plata. 
