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U. S, P. R. R. EXP. AND SURVEYS-ZOOLOGY—GENERAL REPORT. 
PLATICHTHYS, Girard. 
Gen. Char. —Eyes on either the right or left side. Mouth rather small ; snout somewhat produced ; lower jaw longest; 
small and conical teeth on both sides of the jaws. Origin of dorsal fin situated opposite the middle of the orbit; dorsal and 
anal fins not extending to the caudal ; latter posteriorly sub-convex. Surface of head scaly like the body. Lateral line 
slightly arched above the pectoral fins, hence straight to the base of the caudal. 
Svn. — Platichthys, Grd. in Proc. Acad. Nat. Sc. Philad. VII, 1854, 139 ; and, VIII, 1856, 136. 
This genus has the general aspect of Rhombus , from which it differs by a smaller mouth, a 
dorsal fin beginning above the orbit, and by both the dorsal and anal fins being separated from 
the caudal. The scales, moreover, have a proclivity of becoming quite prickly and rough to the 
touch. 
To this genus belongs Pleuronectes stellatus of Pallas, 1 or Platessa stellata of modern writers. 2 
The latter species is closely allied to P . rugosus, described further on, from which it may even 
not differ. An actual comparison between the specimens is, however, demanded, before a 
settlement of the question can be arrived at. 
1. PLATICHTHYS RUGOSUS, Grd. 
Spec. Char. —Eyes moderate, situated on the left side. Interocular space moderate. Peduncle of tail long. Origin of 
dorsal fin corresponding to a vertical line intersecting the middle of the pupil. Scales very rugose and plate-like. Lateral line 
slightly arched above the pectoral fins. Left side dark reddish brown ; fins olivaceous, dorsal and anal with alternate vertical 
bands of black, caudal with longitudinal bands of the same hue. Ventrals and pectorals unicolor. Right side dull yellow. 
Syn. —Platichthys rugosus, Grd. in Proc. Acad. Nat. Sc. Philad. VII, 1854, 139 and 155. 
The general form of the body is sub-elliptical, leaving out the snout and the peduncle of the 
tail. The head, which is of medium size, constitutes about the fourth of the total length, which 
measures nine inches in the specimen we describe. The occiput is very much depressed, the 
snout sub-conical, the lower jaw being the longest and protruding beyond the upper. A row of 
short, conical teeth may be observed on either side of the jaws. The posterior extremity of the 
maxillary extending somewhat beyond the anterior rim of the orbit, approximating it closely 
when the mouth is shut. The eyes are moderate sized and, as a general rule, situated on the 
left side ; they are sub-elliptical and their horizontal diameter contained about six times in the 
length of the side of the head. The interocular space is of moderate width. The branchios- 
tegals are seen on either side. 
The origin of the dorsal fin takes place upon a vertical line which would intersect the pupil of 
the upper eye. Its rays increase in height to the posterior third of its length, hence diminishing 
again to the terminus of the fin. The origin of the anal corresponds to a vertical line drawn at 
some distance behind the base of the pectorals, terminating evenly with the dorsal, at a 
considerable distance from the insertion of the caudal, giving the tail a rather long peduncle. 
The caudal fin itself is posteriorly rounded or sub-truncated, constituting a little less than the 
fifth of the total length. The ventrals are inserted somewhat in advance of the base of the 
pectorals, their posterior extremity not extending quite as far as the anterior margin of the 
1 Zoographia Rosso-Asiatica, III, 1831, 416. 
2 The Zoology of the Voyage of H. M. S. Herald. Reptiles and Fish, 1854, 164. 
