338 SPINE-FINNED GROUP. 



the common species ranging- from Britain through Central Europe to Siberia. 

 The " pope," as the ruffe is frequently called in England, is common in most of the 

 rivers and canals of that country, generally preferring slow, shaded streams, with 

 a gravelly bottom, and closely resembling the perch in its mode of life. 



Family Here may be mentioned a small family, with ten genera of 



Centrarchidse. perch-like fishes, distinguished from the Percidce and the following 

 family by the mode of attachment of the ribs, which, with the exception of the 

 last, or last two or four, are inserted on the bodies of the vertebras behind the 

 transverse process, instead of the process itself ; all the vertebras in front of the 

 tail, save the first two or three, having such processes. Externally these fishes 

 differ from the perches in the presence of at least three spines in the anal fin. 

 The family is typified by the North American genus Centrachus, of which there 

 is but a single species. All are carnivorous fresh- water fishes, sometimes entering 

 estuaries, and many are in the habit of building nests for the protection of their 

 young. 



Bass and Sea-Perches, — Family Serranid^-e. 



Although usually included in the Percidce, with which they agree in the 

 structure and relations of the vertebras and ribs, the sea-perches and their allies 

 are regarded by Mr. Boulenger as representing a family by themselves, on account 

 of the circumstance that the second suborbital bone develops an internal plate for 

 the support of the eye. The number of spines in the anal fin is variable : and in 

 one genus (Centrogenys) the lower pharyngeal bones are united. The family is 

 a very extensive one, and may be divided into several subfamily groups. 

 South American Together with the sea-perches, the bass represent a subfamily 



Perch and Bass. (Serraninw) - presenting the following characteristics. The upper 

 jawbone, or maxilla, is exposed, its upper border not being entirely concealed b} r 

 the overlapping preorbital ; the scales are not shed ; there is no scaly process at 

 the bases of the pelvic fins ; the anal fin has three spines ; the gill-membrane is 

 free behind ; and the false gills are well developed. In distribution the subfamily 

 is cosmopolitan, and while most of the forms are marine, a few inhabit fresh 

 water. Among the latter may be mentioned the South American perch 

 (Percichtftys), of Chili, Western Argentina, and Patagonia, which, in common with 

 five other genera, has a divided dorsal fin. From an ordinary perch these fish 

 may be distinguished by the scaly upper surface of the head, and the presence 

 of nine or ten spines in the first dorsal, and three in the anal fin. To this section 

 of the subfamily also belong the bass (Morone), which are partly marine and partly 

 fresh- water fishes, easily distinguished from the true perch by having only nine 

 spines in the dorsal fin, while there are usually three in the anal. There are also 

 teeth on the tongue ; and while the preopercular bone is serrated, with denticula- 

 tions on its lower border, the front border of the preorbital bone is entire. 

 The scales are rather small, and extend all over the head. Of the three European 

 and Atlantic species, which are almost entirely marine, the best known is the 

 common bass (J/, labrax), represented in the upper figure of the illustration 

 on p. 339, and characterised by its extreme voracity and fierceness. Elsewhere, 

 the genus is represented by fresh-water species from the rivers of the United 



