FISHES — PLEUEONECTIDAE — PLEURONICHTHYS COENOSUS. 



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1. PLEURONICHTHYS COENOSUS, Grd. 



Si>Ec. Char. — Body sub-clIiptical. Posterior extremity of maxillary extending to a vertical line drawn midway between the 

 pupil and the anterior rim of the orbit. Origin of dorsal fin curved towards Ihe left side of the head, and corresponding to the 

 anterior rim of the upper orbit on the right side. Ground color olivaceous brown, macul ited 



Syn. — PleuroniclUhys coenosus, Grd. in Proc. Acad. Nat. Sc. Philad. VII, 1854, 139. 



The body is sub-elliptical, the head quite small, and the snout very short and blunt, the lower 

 jaw being longer than the upper, and the mouth rather small, with its gape oblique. Minute, 

 conical, and acute teeth may be observed on either side of the jaws. The posterior extremity of 

 the maxillary extends beyond the anterior rim of the orbit, without, however, reaching a vertical 

 line drawn in advance of the pupil. The eyes, which are situated on the right side, are large 

 and sub-elliptical ; their longitudinal diameter entering about three times in the length of the 

 side of the head. The interocular space is very narrow and ridge-like. The bead itself is con- 

 tained about five times and a half in the total length of the fish. The branchial apertures are 

 moderate, and not contiguous under the throat. 



The origin of the dorsal fin, which is bent towards the left side, takes place opposite the 

 anterior rim of the upper orbit ; it is quite elevated towards its posterior third, generally speak- 

 ing well developed, and terminated at a short distance from the insertion of the caudal. The 

 origin of the anal corresponds to a vertical line drawn posteriorly to the base of the pectorals, 

 increasing in height towards its middle, and terminating evenly with the dorsal. The rays of 

 both the dorsal and anal fins are rather stoutish, not bifurcated and provided on the left side 

 with a membranous expansion which overlap each other when the fins are inclined backwards. 

 The peduncle of the tail is very short and stright. The caudal fin, which constitutes a little 

 less than the fourth of the total length, is rounded or convex upon its posterior margin. The 

 insertion of the ventrals is placed in advance of the base of the pectorals ; they are broad and 

 rather short, although extending beyond the anterior margin of the anal ; their rays are not 

 bifurcated. The pectorals are moderate sized, the left being somewhat smaller than the right, 

 with a less decided bifurcation of its rays. 



Br. VI : VI ; D 74 ; A 54 ; C 3, 1, 7, 6, 1, 4 ; V 6 ; PI, 10. 



The body is covered with small scales, somewhat smaller on the left than on the right side ; 

 they are sub-elliptical, longer than deep, and posteriorly entire and smooth instead of being 

 pectinated. Over the opercular apparatus and head they are smaller also than on their respective 

 side. Those occupying the base of the caudal are likewise diminutive and irregularly shaped. 

 The lateral line, which is nearly straight, is slightly raised into a depressed curve immediately 

 above the pectoral fins. 



The ground color of the right side is deep brown, maculated with blackish and yellowish ; the 

 left side is of a uniform soiled yellow. 



The specimen described, the only one that has fallen under our investigations, measures seven 



and a half inches in total length. 



List of specimens. 



