S A U R I A. 



regions are whitish or yellowish, with elongated brownish or blackish 

 spots under the head and throat. 



a _ The species is exceedingly abundant among the sandhills on 

 the coast of Patagonia, where specimens were collected in February, 

 1839, when a colored sketch of the female was made by Mr. Drayton. 



Plate XVII, fig. 22, represents the profile of the female of Ptycho- 

 deira gracilis, size of life. 



Fig. 23, exhibits the same specimen, from beneath. 



Fig. 24, is an upper view of the head ; 



Fig. 25, a front view of the same. 



Fig. 26, the left hand, seen from above. 



Fig. 27, a group of dorsal scales ; 



Fig. 28, a group of abdominal scales. 



Figs. 24-28, are somewhat magnified. 



2. PTYCHODEIRA FEMORATA, Grd. 



SPEC. CHAR. Cephalic plates rugose. Auricular aperture moderate, 

 denticulated. Supralabials much narrower than the labials. Tem- 

 poral scales moderate. Sides of the neck slightly wrinkled. Dorsal 

 scales diminishing in size towards the sides. Abdominal scales 

 smooth, posteriorly rounded. Tail elongated and slender. Brown- 

 ish, with two parallel light streaks on each side, and two series of 

 black spots. Abdomen whitish, unicolor. Inferior surface of head 

 exhibiting interrupted greyish lines. 



SYN. Proctotretus femoratus, GRD. in Proc. Acad. Nat. Sci. Philad. VII, 1854, 

 227 j &, in Gillit, U. S. N. Astr. Exped. S. Hemisph. II, 1855, 219. PI. XL, figs. 5-12. 



DESCR. The head is depressed, and quite declivous from the fron- 

 tal region towards the snout ; viewed from above, it is subtriangular, 

 subtruncated anteriorly. The cephalic plates are of moderate deve- 

 lopment, exhibiting, upon their surface, sinuating, subtubercular ridges, 

 which give to that region a rugose appearance. The vertex plate, a 

 pair of postoccipitals, and two pairs of postfrontals may be distin- 

 guished, amid their number, as larger than the rest. Three post-inter- 



