NATURAL SCIENCES OP PHILADELPHIA. 57 



Description. The head is depressed ; the snout rounded ; the temples swollen ; 

 the nostrils, which are large, are situated in a depression between two plates ; 

 the eyes prominent, latero-superior, circular, the pupil ovoid, perpendicular ; 

 the rostral plate is pentangular, much more broad than high ; the internasala 

 are of moderate size, the prefrontals of much greater dimensions, their external 

 and inferior border in contact with the frenal, their posterior with the antocular, 

 the supra-ocular and the frontal plates ; the supra-ocular are pentangular, much 

 more narrow anteriorly ; the frontal is five-sided, its lateral margins scarcely 

 excavated, its posterior angle moderately obtuse, two and a quarter lines in 

 length by about one and a half in breadth ; the parietals are three lines in length 

 by two in breadth, much more narrow posteriorly ; the frenal is rathf r long and 

 of moderate breadth, in contact inferiorly with the second and third supra-la- 

 bials ; the antocular is larger than either of the three postoculars, and is pent- 

 angular in shape ; there are two rows of temporal plates, surmounted by a 

 third, of which the posterior is the largest ; there are nine superior labials, the 

 eye resting on the fourth and fifth ; no two are precisely alike, the first is the 

 smallest, the seventh pentangular, a line in breadth by half a line in height ; 

 there are seven inferior labials, each differing more or less in shape, and of 

 which the fourth is of much greater dimensions than either of the others; the 

 mental is triangular, the accessory labials rather long, the first geneial much 

 larger than the second. The neck is much more narrow than the head, is rather 

 long and slender; the body of very moderate thickness; the tail one-fifth of 

 the total length. There are 15 to 17 rows of smooth scales near the middle of 

 the body, 18 upon the neck, 12 near base of tail ; the scales are short and quad- 

 rangular upon the middle, more narrow upon the neck, broad upon the tail ; 

 the scales constituting the dorsal row are considerably larger than the 

 adjoining rows, and each scale is hexagonal in shape ; this larger row extends 

 upon the tail, but in the specimen examined appears to be interrupted near its 

 root. Ab. scut. 221 ; 1 single preanal ; 81 bifid sub-caud. 



Dimensions. Length of head 9 lines; greatest breadth .5.V; length of body 1 

 foot 8 inches 7 lines ; length of tail 5 inches. Total length 2 feet 2 inches 4 

 lines. 

 Habitat. Gaboon, west coast of Africa. 



Gen. Remarks. The outline of the head and the general arrangement of the 

 plates, has a certain resemblance to the figure of Lycodon audax (Lycognathus 

 scolopax, D. and B.) in the altas accompanying the Physiognomie des Serpens 

 of Prof. Schlegel, pi. iv. fig. 18, but it is quite a different serpent from the latter, 

 which is found in South America. It has also a certain relation, in the general 

 disposition of the plates upon the head and teeth, with Lycognathus cucuUatas, 

 a North African serpent, but a comparison of the two proves at once that they 

 belong to different genera. The outline of the head, the relative proportions of 

 the internasals and prefrontals, and the form of the frontal plate, are very dif- 

 ferent ; the nostrils are deeply excavated in Hormonotus ; in cucullatus there is 

 no larger dorsal row, and the scales are shorter, &c. It is also a much smaller 

 animal. 



The species which remains to be described is a quite different looking serpent 

 from the last, presenting a series of generic characters quite remarkable, more 

 especially the form of the frontal plate. 



Gen. Char. Head cuneiform, eyes small, two small inter-nasals, two large pre- 

 frontals, a frontal about as broad as long, presenting an acute angle posteriorly ; 

 nostril in a single plate at its posterior margin, two nasals, a frenal, one 

 antocular, two postoculars, seven superior labials, the eye resting on the third 

 and fourth ; several small teeth on the upper jaw, followed by a much larger 

 one, after which an interspace, succeeded by a row of small and nearly equal 

 teeth ; maxillaries of lower jaw presenting a corresponding system of dentition ; 

 but the interspace behind the larger teeth do not exist apparently ; body 

 nearly the same thickness as head ; tail short; scutes bifid. 



1857.] 



