220 ZOOLOGY. 



and sharper teeth. In it is the species H. vulgaris, or halibut, found on 

 the coasts of both Europe and America. It attains to a very large size, 

 individuals of even 500 and 600lbs. having been met with. Its flesh is 

 highly prized, and the fins are world-renowned as an epicurean morsel. In 

 Rhombus both the eyes and color are on the left side : the dorsal com- 

 mences anterior to the eye : dorsal and anal fins extend nearly to the tail. 

 Teeth exist both in the jaw and pharynx. Conspicuous in this genus is 

 Rhombus maximus, or the turbot, celebrated as the best of all European 

 fishes. A turbot, probably of a different species, has recently been 

 detected off' the coast of Massachusetts. PL 81, j^^. 8, represents 

 Rhmnbiis vulgaris, or the brill, a common European species. The genus 

 Achirus is without pectoral fins, and has the eyes on the right side of the 

 head. Mouth distorted to the side opposite the eyes, and very small. Dorsal 

 and anal not united to the tail, as is the case in the genus Plagusia. The 

 Achirus mollis, or common sole, is very abundant on the Atlantic coast of the 

 United States. PL 82,ßg. 11, represents the Solea vulgaris, European sole. 



The family Echineid^ is represented by the genus Echineis, which 

 comprehends fishes with a flattened disk upon the top of the head ; this 

 being composed of a variable number of cartilaginous plates, movable in 

 such a manner as to admit of their being attached by suction to an object 

 in the water. A single dorsal opposite the anal. Teeth on the jaws, 

 vomer, and tongue. PL 84, fig. 3, represents the Echineis remora, or 

 sucking-fish, found throughout the Atlantic ocean. There are additional 

 species with various characters. 



We come now to an order of fishes, Acanlhopteri, corresponding nearly 

 with, but rather more restricted than, Acanthopterygii of Cuvier. This 

 order is characterized by the ctenoid scales, the advanced ventrals, the 

 spinous fins. &c. It embraces many species of considerable value. The 

 first family, Percid.e, is known by the rough scales, the dentated oper- 

 culum or preoperculum, and the occurrence of teeth in the jaws, the front 

 of the vomer, and generally on the palatines. 



The number of genera and species in this family is very great, distributed 

 as they are over the entire globe, and occupying both salt and fresh water. 

 Two principal types may be distinguished, one with a single continuous 

 dorsal, the other with this dorsal more or less deeply divided, and separated 

 into two. The typical genus is that of Perca, with two separated dorsals, 

 the rays of the first spinous, of the second flexible ; teeth in both jaws, in 

 front of the vomer, and on the palatines ; tongue smooth ; operculum with 

 a short, flattened, backward spine. Perca fluviatilis, the most common 

 European species, is figured in pi. 82, fig. 4. Numerous species occur in 

 North America, the most conspicuous of which is the Perca fiavescens, or 

 common vellow perch, which is found in almost all sorts of situations, both 

 salt-water and fresh. Several closely allied species occur in the different 

 lakes and rivers of the North American continent. The genus, or rather sub- 

 family, Etheostoma, is altogether peculiar to North America, where nearly 

 every large river has one or more species peculiar to it. They are all of 

 rather small size, some of them very minute. Professor Agassiz has recently 

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