XENODON ANCORUS. 167 



Log. — The specimen described was obtained in the vicinity of Sin- 

 gapore. 



Xenodon" ANCORUS, Grd. 



Char. spec. — Scutis praeorhitalibus et postorhitalihus duohus. Squamia 

 laevihus in septendecim series longitudinales dispositis. Supra spadiceo, 

 cum maculis transversis per notaeum ordi7iatis, et in capite macula an^ 

 coriforme ; infra unicolori. 



Spec. Chae. — Two anteorbital and two postorbital plates. Scales 

 smooth, disposed upon seventeen longitudinal series. Brownish- 

 red above, with transverse blotches along the back, and an anchor^ 

 shaped spot upon the head. Beneath unicolor. 



Syn. — Xenodon ancorus, Grd. in Proc. Acad. Nat, Sci. Philad. August, 1857, 182. 



Obsery.— This species is allied to X. purpurescens, from which it 

 differs by the presence of seventeen dorsal rows of scales instead of 

 nineteen, and by the pattern of coloration also. 



Descr. — The head is rather short, stoutish upon the occiput, sub- 

 conical forwards, and truncated in front ; it is declivous laterally and 

 posteriorly, passing gradually to the neck, which is nearly as thick 

 as the body. The rostral plate is large, subpyramidal, deeply e mar- 

 gin ated upon its base, and extending to the upper surface of the head. 

 The prefrontals are smaller than the postfrontals, all of which are sub- 

 angular in shape. The supraoculars are angular, narrower anteriorly 

 than posteriorly. The vertex plate is hexagonal and broad. The 

 occipitals are the largest of the cephalic plates. The nasal is well 

 developed, broader anteriorly than posteriorly, near which margin the 

 nostril is perforated. The loral is conspicuous, and angularly subellip- 

 tical. The inferior anteorbital is very small ; the upper one is angular, 

 equal in size and shape to the upper postorbital, whilst the lower post- 

 orbital is narrower and more elongated or elevated, resting upon the 

 sixth labial. The eye is of medium size, with a circular pupil. There 

 are three or four temporal shields, larger than the scales immediately 

 behind. The upper labials are eight in number, and much more deve- 



