4 
U. S. P. R. R. EXP. AND SURVEYS-ZOOLOGY-GENERAL REPORT. 
DIOPLITES, Rafin. 
Gen. Char. —Body elongated, sub-fusiform in profile ,compressed. Head well developed. Preopercle smooth and entire. 
Mouth large ; lower jaw longest. Velvet-like teeth on the jaws, front of vomer, and palatine bones. Tongue smooth. Cheeks 
and opercular apparatus scaly. Branchial apertures continuous under the throat. Two dorsal fins contiguous upon their base. 
Three small anal spines. Insertion of ventrals on a line immediately behind the base of pectorals. Caudal fin posteriorly suh 
crescentic. Scales well developed and posteriorly ciliated. 
Stn. — Dioplites, Rafin. Ichth. Ohiens 1820, 35. 
Grystes, Cuv. & Val. Hist. Nat. P iss. Ill, 1829, 54. 
The fishes of this genus are not uncommon in the localities where they occur. They resemble, 
in general appearance, the common or yellow perch, though often reaching a much larger size. 
They are esteemed as an article of food, and known under the general appellation of “trouts” 
or “bass.” Exclusively of fresh water habits, they are met with in ponds and rivers, asso¬ 
ciated with various kinds of suckers, chubs, daces, minnows, &c., upon which they teed. 
They are remarkable in the percoid family for their general smooth appearance, having 
neither spines nor serratures upon the opercular apparatus. The scales themselves are but 
slightly pectinated, and the few pectinations are quite deciduous or falling off with the 
epidermis. Their teeth are all uniform and velvet-like, and exist upon the palatine bones as 
well as upon the vomer, premaxillaries (upper jaw), and dentaries (lower jaw). The mouth, 
is generally large, with its gape slightly oblique upwards, and the lower jaw protruding beyond 
the upper. The tongue is generally smooth anteriorly, but an elongated and narrow patch of 
velvet-like teeth is occasionally observed upon the middle line at the base of that organ. 
A feature peculiarly characteristic of this genus, when associated with its other natural 
characters, consists in the separation of the spinous portion of the dorsal from the soft portion, 
by a wide gap, so that we have in reality two fins, contiguous upon their base only. This fea¬ 
ture appears to constitute the chief difference between Dioplites and Calliurus, not taking into 
account the gene ral aspect of the body, which has a subordinate value. 
The species enumerated below appears to be very common in Texas, and even south of the 
Rio Grande del Norte (Rio Bravo), as proved by the specimen collected by Lieutenant D. N. 
Couch, United States army, in the Rio San Juan, near Cadereita, province of New Leon. 
We have examined two immature specimens of another species—perhaps D. salmoides ; one 
collected at New Braunfels, Texas, by Dr. Lindheimer, the other in the Rio Brazos, Texas, 
by Dr. G. C. Shumard, and which must await another opportunity for a more critical 
determination. 
DIOPLITES NUECENSIS, Grd. 
Trout, or River Bass. 
Spec. Char. —Body elongated, sub-fusiform. Head constituting a little less than the third of the entire length. Posterior extremity 
of maxillary extending to a vertical line drawn posteriorly to the orbit. Scales on the cheeks nearly equal in size to those on 
the gill covers. Origin of ventrals posterior to the brse of pectorals. Upper regions reddish brown, maculated. A lateral dark 
band. Inferior regions whitish, unicolor. 
Syn. — Grystes nvecencis, B. & G., in Proc. Acad. Nat. Sc. Philad. VII, 1854, 25. 
Trout, or River Bass, Vernacular. 
A full description and a figure of this species will be found in the Ichthyology of the United 
States and Mexican Boundary Survey. 
It is closely related to, if not identical with, Grystes nobilis, Agass., from the southern bend 
