ACANTHOPTERYGII. 193 



A second division comprises Percoides with seven branchial rays and one 

 dorsal. They are subdivided in nearly the same way as the preceding ones, as 

 by their teeth, which are either hooked or ah 1 small and crowded ; notches and 

 spines on the opercula, &c. 



In the subdivision, furnished with hooked teeth, we find 



SERRANUS, Cuvler. 



Preoperculum dentate; the bony operculum terminating in one or several 

 points. This genus contains a vast number of species, and is divided into 

 several subgenera. 



We now pass to Percoides with seven branchial rays, and a single dorsal, 

 the teeth small and crowded. 



They are distributed under the genera Acerina, Rypticus, Centropristis (to 

 which belongs our Black Perch), and Gristes. 



The genus PERCA, as defined by Artedi and Linnseus, terminates here ; but 

 there remains a number of fishes which approach it, although peculiar charac- 

 ters compel naturalists to arrange them in separate genera, such as Cirr/iites, 

 Chironemus, Pomotis (our Pond-Perch) , Centrarchus, &c. &c. 



POMOTIS, Cuvier. 



Fishes, with a compressed and oval body, characterised by a membranous 

 prolongation at the angle of the operculum. They inhabit the rivers, &c. of 

 America, where they are called Pond-Perch. 



We now pass to those Percoides which have more than seven rays to the 

 branchiae. Three genera are known, ah 1 of which present the following pecu- 

 liarity : their ventrals have a spine and seven or more soft rays, while in other 

 Acanthopterygii there are never more than five soft rays. 



HOLOCENTRUM, Artedi. 



The scales of these beautiful fishes are brilliant and dentated ; operculum 

 dentated and spinous ; preoperculum dentated with a stout spine at the angle, 

 which is directed backwards. They are found in the hot parts of both oceans. 



MYRIPRISTIS, Cuvier. 



The brilliancy, shape, and scales of the Holocentra ; but the preoperculum 

 has a dentated double border, and there is no spine at the angle. They 

 inhabit the hot parts of both oceans. 



BERYX, Cuvirr, 



Differs from Myripristis in having but a single short dorsal, with but a few 

 small spines, almost hidden in its anterior edge ; ten soft rays in the ventrals. 

 All the Percoides of which we have hitherto spoken have their ventrals 

 inserted under the pectorals ; there are some genera, however, in which they 

 are differently located. 



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