FISHES. 37 
Desc. The body is elongated, subquadrangular or subrounded upon its anterior half, very 
much compressed posteriorly, and thinning off towards the base of the caudal fin. The greatest 
depth, measured in advance of the dorsal fin, is about the eighth of the entire length, whilst 
the least depth, immediately behind the anal, enters nine times and a half in the same dimen- 
sion. The greatest thickness, at the origin of the trunk, is equal to the least depth, and the 
thickness above the anal fin is contained nearly three times and a half in the depth upon that 
same region. The head constitutes about the fifth of the total length. It is very much 
depressed, and broader than the body anteriorly. Its depth upon the occipital region is a little 
less than the half of its length, hence tapering off to the extremity of the snout, being also 
declive towards the sides. The mouth is broad, though not deeply cleft; the posterior extremity 
of the upper maxillary reaching a vertical line which would pass a little nearer to the anterior 
rim of the eye than to the posterior nostril. The jaws are nearly equal, and surrounded with 
well developed membranous lips, expanding considerably towards the angle of the mouth, where 
a subcylindrical barbel is observed, which extends posteriorly beyond the base of the pectoral 
fins. A pair of flattened barbels may be observed under the head, attached to the anterior part 
of the hyoidal apparatus, each widely separated from one another. When stretched backwards 
in a straight line from their insertion, their tip reaches the edge of the branchiostegal mem- 
brane. The nostrils, right and left, are wide apart; the anterior is much the largest, situated 
close to the jaw, and provided at its upper and posterior rim with a flattened and tapering 
barbel about seven twentieths of an inch long, immediately behind which may be seen the pos- 
terior opening, subcircular in shape, and provided upon its upper and posterior rim with a 
membranous expansion sufficiéntly large to cover that aperture when let down upon it. The 
eyes, situated towards the upper surface of the head, are small, inconspicuous, and elongated; 
their longitudinal diameter measuring but a quarter of an inch; their posterior rim being nearly 
equidistant between the margin of the upper jaw and the posterior edge of the opercular appa- 
ratus. An oblong and rather large patch of card-like teeth exists upon the intermaxillaries ; 
the upper maxillaries being toothless. A broad band, posteriorly tapering, of similar but 
smaller teeth, may likewise be seen upon the dentary or lower jaw. The roof of the mouth is 
smooth; but at the entrance of the esophagus the pharyngobranchials, upper and lower, are 
possessed with teeth of the same description, but smaller still than those of the dentaries, 
becoming almost velvet-like. The upper pharyngobranchials are subelliptical in shape and 
convex, whilst the inferior pair of these bones are subtriangularly elongated and subconcave. 
A double row of conical processi are observed, one upon each side of the branchial arches ; the 
anterior row more developed than the posterior one. The tongue is short, and provided on each 
side with a fleshy expansion. The opercular apparatus is concealed under the skin, without 
either spines or serratures of any kind. The branchial apertures are broadly open, and split 
to the hyoidal apparatus, without any intermediate membrane connecting the right and left 
flaps. The branchiostegals are numerous and slender, those next to the opercular apparatus 
are flattened, the others circular—all more or less curved. The membrane which unites them 
extends beyond their tips. 
The anterior margin of the dorsal fin is nearly equidistant between the extremity of the snout 
and the base of caudal. That fin is higher than long, superiorly convex; its central rays are 
subdivided three times. The anal resembles the dorsal in general appearance, being deeper 
than long, but more acuminated posteriorly. Its central rays bifurcate, likewise, thrice, and 
their tips reach the rudimentary rays of the caudal, between the base of which and the origin of 
ventral its anterior margin corresponds. The caudal, which constitutes a little less than the 
sixth of the entire length, is broad and rounded posteriorly; its central rays bifurcate three 
times upon their length; there are numerous rudimentary rays above and below. The insertion 
of the ventrals is nearly opposite to the anterior margin of the dorsal. These fins are of medium 
size, exteriorly rounded when expanded, and their rays three times bifurcated. The pectorals 
are longer and narrower than the ventrals, and inserted near the inferior surface of the body ; 
6 
