CHAPTER XVIII 
PERCOIDEA, OR PERCH-LIKE FISHES 
WIERCOID Fishes—We may now take up the long 
series of the Percoidea, the fishes built on the type 
weit] of the perch or bass. This is a group of fishes of 
dee habits and forms, but on the whole representing better 
than any other the typical Acanthopterygian fish. The group 
is incapable of concise definition, or, in general, of any defini- 
tion at all; still, most of its members are definitely related 
to each other and bear in one way or another a resemblance 
to the typical form, the perch, or more strictly to its marine 
relatives, the sea-bass, or Serramide. The following analysis 
gives most of the common characters of the group: 
Body usually oblong, covered with scales, which are 
typically ctenoid, not smooth nor spinous, and of moderate 
size. Lateral line typically present and concurrent with 
the back. Head usually compressed laterally. and with the 
cheeks and opercles scaly. Mouth various, usually terminal 
and with lateral cleft; the teeth various, but typically pointed, 
arranged in bands on the jaws, and in several families on the 
vomer and palatine bones also, as well as on the pharyngeals; 
gill-rakers usually sharp, stoutish, armed with teeth, but some- 
times short or feeble; lower pharyngeals almost always separate, 
usually armed with cardiform teeth; third upper pharyngeal 
moderately enlarged, elongate, not articulated to the cranium, 
the fourth typically present; gills four, a slit behind the fourth; 
gill membranes free from the isthmus, and usually not con- 
nected with each other; pseudobranchize typically well 
developed. Branchiostegals few, usually six or seven. No 
bony stay connecting the suborbital chain to the preopercle. 
Opercular bones all well developed, normal in position; the 
preopercle typically serrate. No cranial spines. Dorsal fin 
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