10 
ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 
Proctotretus nigromaculatus. 
Plate IV. — Fig, 2. 
Capite hrevi, squamis neque imbricatis nec carmatis, tecio ; aurihus margine anteriore 
tridentato ; serie unicd squamarum supralabialium ; squamis temporum magnis, 
rotundatis, imbricatis ; colli {et prcecipuh plicce) crassis, elevatis ; facie posteriore 
femorum omnind granulosa ; squamis nonnullis ad latera abdominis gulceque emargi- 
natis ; macula transversh oblonga, nigra, supra regioneni scapidarem. 
Tropidurus {Leiolaemus) nigromaculatus, Weigm. Act. Acad. Cses. Nat. cur. xvii. p. 229. 
Proctotretus nigromaculatus, Bibr. 1. c. p. 281. 
Habitat, Coquimbo, Chile. 
Description, — Head short, the muzzle rounded, rather obtuse ; scales of the upper part of the head 
somewhat convex, smooth ; a single line of scales between the labial and orbitar ; ears rather 
large, the anterior margin having three rather prominent scales, the middle one being the 
largest. Temporal scales somewhat large, smooth, rounded, and imbricated, those towards the 
upper part slightly carinated ; those of the sides of the neck thick and elevated, those on the 
fold being rather acutely prominent ; scales of the back carinated, the carina terminating in an 
acute point ; a few of the scales at the sides of the abdomen and throat notched ; the remainder 
of the scales of the under parts rhomboidal. The scales about the axilla and around the base 
of the shoulder are granular and very small, as are those of the posterior surface of the thighs, 
on which part there are no imbricated scales as in Tr. Fitzingerii. The tail is round, excepting 
at the base where it is slightly flattened ; it is moderately long and slender. The anterior 
extremity placed against the side does not reach to the thigh ; the posterior similarly placed 
reaches to the shoulder. The colour of this species is yellowish grey above, with a yellowish 
longitudinal line on each side the back, and two rows of black spots each margined with yellow 
behind. There is a large and distinct oblong black mark on the region of the scapula, from 
which circumstance the species takes its name. On the posterior surface of the thighs, towards 
the upper part, are three or four black dots placed in a line. The under surface is yellowish 
white with dark grey dots and lines under the chin and throat. 
DIMENSIONS. 
Inches. Lines. 
Length of the head 0 5 
of the body 1 5 
of the tail 2 8 
Total length .... 4 8 
Length of anterior extremity 0 8 
of posterior extremity 1 2 
This species was first described by Weigmann, and subsequently by M. 
Bibron, from specimens obtained by Gaudichaud from Coquimbo, at which place 
the single specimen brought home by Mr. Darwin was also obtained. 
