REPTILES. PHY 
SAURIA. 
FAMILY OF STELLIONIDAE. 
Genus PROCTOTRETUS, Dum. & B. 
Gen. cHAR. Body rounded or slightly depressed, covered with imbricated scales ; the upper 
ones carinated, the inferior ones generally smooth; neither a dorsal nor a caudal crest; head 
subpyramido-quadrangular, more or less depressed; cephalic plates moderate, polygonal ; oc- 
cipital generally not very conspicuous; teeth on the palate; sides of neck either folded or smooth; 
no subgular fold; an ear opening; membrane of tympanum but little depressed; fingers simple; 
tail either long or conical, or moderate and slightly depressed; no femoral pores; anal pores in 
the males. 
Syn. Proctotretus, Dum. & B. Erp. gén. IV, 1837, 266. 
Gutcu. in Gay, Hist. de Chile, Zool. II, 1848, 28. 
PROCTOTRETUS TENUIS, Dum.an B. 
Prate XL, Figs. 1—4. 
Spec. cHar. Cephalic plates usually smooth, occasionally covered v. ith very minute granules. 
Auricular aperture large; its anterior margin subtubercular. One series of supralabials. Tem- 
poral plates irregularly rounded, subimbricated, subtuberculous, and of moderate development. 
Sides of neck folded and granular. Dorsal scales small, carinated, and posteriorly obtuse ; 
lateral scales smaller, not imbricated, provided with a rudimentary carina; abdominal scutelles 
smooth and mostly entire. Posterior surface of thighs minutely granular. Tail long and 
slender. Brownish-black, with transverse subcrescentic black bands. 
Syn. Proctotretus tenuis, Dum. & B. Erp. gén. IV, 1837, 279. 
Bet, Zool. of the Beagle, V, Rept. 1843, 7, Plate ii, fig. 2. 
Guicu. in Gay, Hist. Chile, II, 1848, 32, Erp. Plate 1, fig. 1. 
Homer. and Jaca. Voy. au Pole Sud et dans 1’Océanie, Plate ii, fig. 2. 
Descr. The form, although slender in its general aspect, is less a characteristic of this species 
than it really is for several others of its congenere. The body is depressed; swollen upon its 
middle region; the limbs being of moderate development. The anterior, when stretched along- 
side the body, are far from attaining the groins; and the tip of the longest toe of the posterior, 
when the latter are brought forwards, reaches the middle region of the neck. The tail is elon- 
gated, conical, tapering to a point, and nearly twice as long as the body and head together. 
The tongue is large and fleshy ; elongated in shape and depressed, sublanceolated, occupy- 
ing the entire space between the two branches of the lower jaw. The teeth are of moderate 
development, smallest anteriorly, and subcylindrical; whilst posteriorly these are somewhat 
flattened, or else stouter upon their base. 
The head is depressed, subtriangular in a view from above, and rounded upon the snout. 
The plates which cover its surface are generally smooth, but exhibit sometimes a very minute 
granulation, apparent only through a magnifying glass. The cephalic plates vary as regards 
both their size and number, being smallest when most numerous. In the specimen figured, 
there are three pairs of frontals: one pair of post-occipitals, an odd occipital, a vertical, and 
an odd frontal, which are somewhat larger than the rest, and nearly equal among themselves. 
An inner series of surocularies may be noticed as the next in size; they are separated from 
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