FISHES. 241 



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 sufficiently 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 ; 

 31 * 



