THE MUD- FLOUNDER. 363 



Platessa flesus.* — The Mud-Flounder. 



Specific Characters. — Middle of the back along the course of the 

 lateral Hne, and at the base of the dorsal and anal fins, rough ; sides 

 .smooth. (Plate XXXVn.) 



Description. — From a specimen eleven inches in length. Head 

 rather less than one-fourth of the entire length ; breadth of the body, 

 fins not included, half its length. Colour of the upper surface oliva- 

 ceous brown ; fins rather lighter ; under surface white ; liable to 

 great variation ; occasionally both surfaces are of the same colour ; 

 sometimes the back is yellow or yellowish-brown, marked with dark 

 red spots, and frequently with large white spots ; the colour depend- 

 ing greatl}' on the nature of the soil on which the fish reposes ; if it 

 frequents muddy situations the back is dark ; if sandy places it is 

 more or less red. Dorsal fin commencing over the anterior margin of 

 the orbit, running down the back to within a short interval of the 

 base of the lateral caudal rays, the first ray short, about the length 

 of the diameter of the orbit, the succeeding rays gradually increasing 

 in height to the thirty-fourth, which is the longest, being as long as 

 the base of the eleven first dorsal rays, the rest more rapidly dimi- 

 nishing, the last very small ; caudal fin even or very slightly rounded 

 at the end, the middle ray as long as the base of the first thirteen rays 

 of the anal, all the rays branched except the three lateral ones, which 

 are simple and shorter than the rest. Pectorals rounded, the middle 

 ray the longest, about half the length of the head ; veutrals placed a 

 little in advance of the pectorals ; anal commencing under the middle 

 of the pectorals, and ending in a line under the last ray of the dorsal, 

 the first ray short, the fifteen succeeding ones gradually increasing, 

 from thence gradually diminishing to the last, which is very short, 

 the longest equalling the length of the thirty-fourth ray of the dorsal, 

 a small spine in front of the first ray; snout rather pointed; under 

 jaw longest ; mouth small ; teeth obtuse, jDlaced in a single row ; 

 eyes on the right side of the head equally in advance ; operculum 

 terminating in a point over the base of the pectorals. Lateral line 

 taking a slight curve over the pectorals, from thence running straight 

 to the tail, when it accompanies the lower margin of the middle cau- 

 dal ray ; on each side of the anterior portion of the lateral line are a 

 number of small, rounded, stellated tubercles, giving a roughness to 

 that part when the finger is passed along the lateral line ; the head and 

 cheeks have also a few tubercles of a similar kind; as well as the 

 base of the dorsal and anal fins ; scales of the body small, entire, and 

 very adherent. Number of fin rays — 

 D. 62 ; P. 10 ; V.6; A. 45 ; C. 18. 



• Platessa Jlesus, Yarn, Jen. Pleuronectes Jfesus, Liiiii., Penn. Fresh- 

 water Fluke, Mud-Flounder. 



