t 



ICHTHYOLOGY. 



Family PERCIDAE. 

 DIOPLITES NUECENSIS, G r d . 



Trout or River Bass. 



Plate I. 



Spec. Char— Body elongated, sub-fusiform. Head constituting a little less than the third of the entire lergth. 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 placed posteriorly to the buse of the pectorals. Upper regions reddish brown, 

 maculated. A lateral dark band. Inferior regions whitish, unicolor. 



Syn.— Grystes nuecensis, B. & G. in Proc. Acad. Nat. Sc. Philad. VII, 1854, 25. 



This species is more closely related to D. fasciatus than to D. salmoides, and probably 

 identical with Grystes nobilis, Agass. At any rate the latter has greater affinities with D. 

 fasciatus than with D m salmoides, the latter being restricted to its proper limits. 



The body is proportionally more elongated than in D. fasciatus, resembling more in that 

 respect D. salmoides. It is compressed and sub-fusiform when seen in profile. The greatest 

 depth is somewhat less than the fourth of the total length, in which the head enters a little less 

 than three times. The mouth is more deeply cleft than in any other of the known species of 

 the genus, and its gape is, as usual, oblique upwards, owing to the constant protrusion of the 

 lower jaw beyond the upper, which it does very prominently in this species. The posterior 

 extremity of the maxillary is very much dilated, extending to a vertical line drawn considerably 

 back of the whole orbit. The tongue is large and stout at its base, thinning and tapering 

 towards its apex, which is broadly rounded ; it is smooth anteriorly, being provided posteriorly 

 and upon its middle with a narrow band of velvet-like teeth. Both nostrils are nearer the 

 anterior rim of the orbit than the extremity of the snout ; the anterior one is a little smaller 

 than the posterior, and placed more outwardly with reference to the middle line of the snout. 

 The eye is of moderate development, sub-circular in shape, and reaching the summit of the 

 cranium ; its diameter enters about six times and a half in the length of the side of the head: 

 twice in advance of the anterior rim of the orbit. The opercular apparatus is perfectly smooth 

 and deprived of either spines or serratures. The scales upon the cheeks are but slightly smaller 

 than those covering the opercular pieces. The gill openings are wide and continuous under the 

 throat. 



