] i4 U. S. p. R. R KXP. AND SURVEYS — ZOOLOGY — GENERAL REPORT. 



having priority of puLlication. The only differences which we observe between M. productus 

 and H. iroxohridgii consist in the former having a larger head, and a more anterior situation of 

 the ventral fins. The specimens, however, are not sufficiently well preserved to enable estab- 

 lishing these differences with certainty. 



HOMALOPOMUS TROWBEIDGII, Grd. 



Plate XLa, Figs. 1-4. 



Spec. CiiAn.— Snout pointed ; movitli deeply clefl ; posterior extremity of maxillary extending to a vertical lino drawn 

 through the posterior rim of the pupil Eye large. Second and tliird dorsals continuous ; anal fins continuous also. Extremity 

 of pectorals reaching the anterior margin of the anal fin. Greyish brown above ; silvery grey beneath. 

 Stn. — Homalopomua trowbridgii, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 132. 



The general aspect of the fish is elongated and very much tapering posteriorly. The length 

 of the specimen figured is nineteen inches and a half. The head is sub-pyramidal, entering 

 four times and a half in the total length. The lower jaw is longest, protruding beyond the 

 upper, hence the gape of the mouth is directed slightly upwards. The posterior extremity of 

 the maxillary extends to a vertical line drawn across the posterior rim of the pupil, that is, 

 exactly midway between the tip of the lower jaw and the origin of the pectorals. The pre- 

 maxillaries and dentaries are provided with a double row of canine teeth, largest upon the 

 inner row. The teeth themselves are conical, acerated, and curved inwardly. The symphysis 

 of the premaxillaries is toothless, so that a smooth area is observed at the anterior part of the 

 upper jaw. Small, acerated, canine teeth exist upon the front of the vomer. The palatine 

 bones are toothless. The tongue, broad, thick, fleshy, rounded upon its anterior thin margin, 

 is perfectly smooth upon its surface. The eye is large, sub-circular, its horizontal diameter 

 entering five times in the length of the side of the head. Its posterior rim is nearer the base 

 of the pectoral fins than the extremity of the snout. The nostrils are situated a little in advance 

 of the orbit. The gill openings are broadly cleft, and are continuous under the throat ; the 

 branchiostegal rays are seven in number on either side. The bones of the opercular apparatus 

 are perfectly smooth, there being neither spines nor serrations upon their edges. The limb of 

 the preopercle exhibits a series of very large mucous follicles, not unlike the cavernous bones of 

 Sciaenoids. 



The body is compressed, lanceolated, thickest anteriorly, very much tapering posteriorly. 

 The greatest depth enters about six times in the total length. The peduncle of the tail not 

 occupied by the fins is very narrow ; its termination is spear-shaped, and surrounded by a 

 slender caudal fin, concave upon its posterior margin. The anterior dorsal fin is comparatively 

 small, sub-triangular in general appearance. A vertical line dropped from its origin passes 

 immediately beliind the base of the pectorals. It is composed of ten slender articulated rays, 

 the third of which is the longest ; they bifurcate towards their tips. The second dorsal is 

 continuous with the tliird, there being a depression in the outline to indicate the separation 

 between the two fins. In the specimen now before us, from nineteen to twenty inches long, the 

 second dorsal is separated front the first by a space of half an inch. It is the longest of the 

 three, and also the lowest in the absolute The rays are articulated and bifurcated. The third 

 dorsal is somewhat longer, and a little lower than the first, its rays being more highly bifurcated 

 than in the two preceeding. The caudal is sub-crescentic upon its posterior margin, and 



