PROCTOTRETUS SPLENDID US. 331 



but still, apparently belonging to the sides of the head ; their opening 

 is very conspicuous, perforating the posterior edge of a single, subellip- 

 tic plate, separated from the rostral by two much smaller plates. The 

 rostral itself is low, and broad upon its base, having the shape of a 

 very much depressed cone. The upper labials are four in number, 

 elongated, and narrow. There are two rows of supralabials : the lower 

 one composed of three plates only, elongated, and narrower than the 

 labials themselves ; the upper row is composed of six elongated, quite 

 conspicuous plates. The loral region is occupied by a half dozen of 

 small, snbquadrangular plates. There are three suborbitals : the 

 middle one very large and elongated. The temporal region is covered 

 with rhomboid and carinated scales, similar to those which may be 

 seen on the occiput. The surface of the eyelid is granular, whilst its 

 edge is provided with a double row of small, quadrangular plates. We 

 observe six elongated, nearly equal, lower labials, not quite so narrow 

 as the upper ones. The symphyseal is well developed, laterally con- 

 cave at the commissure of the first labial, and rounded posteriorly. 

 Three pairs of mental shields may be seen, diverging from it. The 

 remaining portion of the throat is covered with quite large, sublanceo- 

 lated, and smooth scales, notched upon their posterior margin. 



The scales on the upper surface of the body are large, subrhomboid, 

 conspicuously carinated, and posteriorly acuminated. A series on 

 either side may be observed extending from the posterior suborbital, 

 along the sides of the neck to the depressed portion of the tail, quite 

 raised above the other, constituting a lateral crest : these inclose a 

 dorsal area of nine series of scales. The middle dorsal series exhibits 

 a more prominent keel than the two adjoining series ; the keels on 

 the third series again are more conspicuous than on the fourth series ; 

 thus, we have, as it were, a tendency to five longitudinal crests, more 

 or less prominent. The sides of the neck are covered with well-deve- 

 loped and carinated scales. A vertical fold of the skin may be observed 

 a little way in advance of the shoulder, directed somewhat obliquely 

 backwards. Between the auricular aperture and the fold just men- 

 tioned, may be seen a series of somewhat raised scales, simulating a 

 horizontal fold. About the axillae, the scales are very small, but cari- 

 nated still. On the upper part of the flank, they are like those of the 

 back, similarly carinated, obliquely disposed, and more acute at their 

 posterior extremity. About the groins, they are larger than about the 

 axillae, and likewise keeled. On the broad and depressed portion of 



