33 s 
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 vertebrae behind the 
transverse process, instead of the process itself; all the vertebrae 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 SeuiianidsE. 
Although usually included in the Percidce, with which they agree in the 
structure and relations of the vertebrae and ribs, the sea-perclies 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. ( Serranince ) presenting the following characteristics. The upper 
jawbone, or maxilla, is exposed, its upper border not being entirely concealed by 
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 
( Percichthys ), 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. 
I he 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 (if. Icibrax), 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 
