148 U. S. p. E. E. EXP. AND SUEVEYS — ZOOLOGY — GENEEAL EEPOET. 



PLATICHTHYS, Girard. 



Gen. Char. — Eyes on cither the right or left side. Mouth rather small ; snout somewliat produced ; lower jaw longest; 

 small and conical teeth on bolli 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. 



Stu. —PlaticlUhys, Grd. in Proc. Acad. Nat. Sc. Philad. VII, 1854, 139 ; and, VIII, 1856, 136. 



This genus lias the general aspect of lihombus, 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,' or Platessa stellata of modern writers.** 

 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 llie pupil. Scales very rugose and plate-like. Lateral line 

 slightly arclicd 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. 



STU.—Platichtliys 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 corftsponds to a vertical line drawn at 

 some distance behind the base of the pectorals, terminating evenly witli 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 



' Zoographia Roaso-Aslalica, III, 18,11, 416. 



' The Zoology of the Voyage of II. M. S. Herald. Reptiles and Pish, 1854, 164. 



