FISH. 139 



than to Rhombus, though possibly it may be found hereafter to serve as the type 

 of a distinct subgenus in this family. The form of the dorsal fin, if correctly 

 delineated, is remarkable. The size of the fish is not stated. 



Rhombus ? 



Form. — Oval, approaching to rhomboidal. Breadth a little exceeding half the length. Eyes 

 on the right side, near together, equally in advance, or the lower one perhaps rather more 

 forward than the upper ; between them a double osseous ridge. On the under side of the 

 head, and nearly answering in position to the upper eye, is a deepish cavity, from whence 

 proceeds a tentaculiform appendage four or five lines in length. Teeth very small, sharp, 

 in scarcely more than two rows, and apparently confined to the under side. Lateral line 

 sweeping over the pectoral. Dorsal commencing above the upper lip, and reaching nearly 

 to the caudal, but leaving a minute space. Both sides of the body are smooth, but the upper 

 one appears to have lost its scales. Pectoral on the eye side about three-fourths the length 

 of the head. 



Length 5 inches. 



Colour. — " Above pale purplish brown, with rounded darker markings." — D. 



Habitat, Bahia Blanca, Coast of Patagonia. 



Achirus lineatus. D'Orbig. 



Achirus lineatus, D'Orb. Yoy. dans L'Amer. Merid. Atl. Ichth. PI. 16. fig. 2. 

 Form. — Body oval, but with the dorsal and anal fins included, approaching orbicular ; the greatest 

 breadth rather more than half the length. Eyes on the right side, moderately near together, 

 the upper one a very little in advance. Lower jaw longest, projecting beyond the snout. 

 Teeth forming a velutine band, very minute, and scarcely sensible except to the touch, 

 confined to the side opposed to the eyes. Preopercle distinct from the opercle. A few short 

 thread-like cirri on the under side of the head ; two at the extremity of the snout being 

 rather longer and more conspicuous than the others. Lateral line nearly straight throughout 

 its course, somewhat higher at its commencement than afterwards, but taking no sweep. Both 

 sides of the body rough, with ciliated scales, but the upper one most so. The dorsal com- 

 mences above the upper lip, and reaches, as also the anal, almost quite to the caudal : this 

 last rounded. Pectorals entirely wanting. 



Length 9 inches. 



Colour. — Not noticed. 



Habitat, Rio Plata. 



This species was obtained by Mr. Darwin in the market at Buenos Ayres, 

 where it is said to be eaten. It so exactly accords in form with the figure of the 

 A. lineatus in D'Orbigny's Voyage, that I have little hesitation in considering it 

 the same, though, from the specimen being dried, there are no vestiges left of the 

 transverse lines. Whether it be the A. lineatus of any other author I am uncer- 



