172 OPHIDIA. 



scribed bv the first pair of labials, which are quite elongated, engaging 

 between the anterior pair of mental shields, exteriorly of which is an- 

 other narrow and long pair, and exteriorly and posteriorly of the latter 

 a third and small pair. The throat is covered with irregular scales. 



The body is subcylindrical and stoutish, much the thickest upon its 

 middle. The tail is but moderately developed, subconical, and taper- 

 ing, forming about the sixth of the total length. 



The dorsal scales are disposed upon twenty-three or twenty-five lon- 

 gitudinal series ; they are lanceolated and strongly carinated, except 

 the external row' on either side, which is smooth and considerably the 

 broadest. The keels do not extend quite to the tip of the scales; 

 the latter being rounded. Fourteen rows of scales may be observed 

 upon the base of the tail. The abdominal scutellae are well deve- 

 loped, one hundred and forty-three to one hundred and forty-seven in 

 number; the preanal one being subdivided. The subcaudal scutellae 

 are disposed upon a double series, from fifty-two to fifty-eight in each. 



The ground color above is greyish-brown, with transverse undula- 

 ting black bars of the width of about one scale, leaving an interve- 

 ning space of about three scales. Black irregular lines are seen upon 

 the upper surface of the head. The snout and lips are spotted with 

 black. There is a fronto-nasal vitta in advance of the eye. A semi- 

 elliptic curve of black may be traced from the interocular region along 

 the temporal region, across the eye to the sides of the neck. The two 

 external rows of scales are generally unicolor, of a yellowish-white hue, 

 the same which extends to the abdominal region, but the row adjoining 

 the scutellae is occasionally covered by the black patches or maculae 

 which are spread all over the belly, the posterior part of which, as also 

 the subcaudal region, are nearly black. 



The color of the back is occasionally of a uniform rusty color, with 

 but one series of black spots above the lateral yellowish stripe. 



Loc. Specimens of this species were caught on Ryan's Hill, near 

 Singapore, in 1841. 



Plate VIII, fig. 8, represents Cerberus boaeformis, size of life. 



Fig. 9, is a profile view of the head. 



Fig. 10, an upper view ; and, 



Fig. 11, an under view of the same region. 



