2 ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 



Thus of the species now described two were known to Weigmann, and de- 

 scribed by him, namely, Chilensis, and nigromaculatus. I received from Capt. 

 King, Chilensis, pictus, cyanogaster, Kingii, Fitzingerii, and, from other sources, 

 Chilensis, pictus, Weigmannii. Bibron describes the whole of these, excepting 

 Kingii, and in addition to them tenuis, pectinatus, signifer. In Mr. Darwin's 

 collection are found all those described by Bibron, excepting signifer; and in 

 addition Kingii now first described, and the following species never before 

 observed, namely, Darwinii, gracilis, Sibronii. 



Although the form of the whole of the species much more nearly approximates 

 that of the Agamidae than most others, they are far removed from that family by 

 several important characters, which it is unnecessary here to detail. 



Proctotretus Chilensis. 



Plate I. — Fig. 1. 



Auribus margins anteriore dentato ; collo nan plicato ; squamis dorsi magnis, rhom- 

 beis ; acute carinatis ; serie unica squamarum supralabialium. 



Calotes Chilensis* Less, et Gam. Voy. de la Coquille, Zool. Rep. t. i. f. 2. 



Tropidurus Chilensis, Weigm. Act. Acad. Cses. Leop. Carol. Nat. cur. xvii. pp. 233. 268. 



Proctotretus Chilensis, Bibr. Hist. Nat. des Rep. IV. p. 269. 



Sun. Tropidurus nitidus, Weigm. 1. c. p. 234, t. xvii. f. 2. 



Var. Tr. olivaceus, lb. 1. c. p. 268. 



Habitat, Guasco in Northern Chile. 



Description. — Head short and broad, rostrum rounded, obtuse. Scales of the head large, and 

 slightly raised, separated by distinct grooves. Superciliary ridge strongly marked, forming a 

 distinct carina, composed of five or six narrow, elongated, obliquely imbricated scales. Nostrils 

 large, nearly round. A single series of narrow scales between those of the upper lip and the 

 orbit. Scales of the temples imbricated, rhomboidal and carinated. The opening of the ear 

 oval, rather large, furnished anteriorly with three or four projecting scales, of which the upper 

 one is the largest. The neck is short, robust and round, and without any lateral fold ; in 

 which it differs from every other species of the genus. The trunk is thick, rounded on the 

 back and sides, flattened beneath, diminishing toward either extremity. The tail is ordinarily 

 almost twice as long as the body, thick at its origin, and tapering regularly to the extremity, 

 nearly round, excepting near the base, where it is slightly quadrilateral. The anterior feet 

 when placed against the sides, extend backwards little more than mid-way between the 

 shoulder and the groin ; the posterior ones, stretched forward, reach the arm-pit. 



The scales of the whole upper and lateral parts of the body, tail, and limbs, are loosely 

 imbricated, large, rhomboidal, and furnished with an elevated carina, terminating in an acute 

 point : those of the under parts are large, smooth, and obtuse. 



