FISHES 273 



Sub-order i. — Spine-finned Fishes (Acanthopterygii). 

 Sub-order 2. — Tuft-gilled Fishes (Lophobranchii). 

 Sub-order 3. — Firm-jawed Fishes (Plectognathi). 

 Sub-order 4. — Soft-finned Fishes (Anacanthini). 



B. — Teleosts in which the swim-bladder retains its connection 

 with the gullet by a pneumatic duct or tube. 



Sub-order 5. — Tube-bladdered Fishes (Physostomi). 



Sub-order i. — Spine-finned Fishes (Acanthopterygii) 



Here as in the Perch, which is a type of the sub-order, some 

 or all of the fin-rays which support the dorsal, anal, and pelvic 

 fins are sharp unjointed spines. Some 3650 different species 

 are here included, divided into about 60 families, of which only 

 a few can be mentioned. 



1. Perch Family (fig. 163). — This is a group of carnivorous 

 fishes, almost entirely confined to fresh water and distributed 

 through the northern hemisphere. 



2. Bass Family. — This is a large group of fishes, which are 

 for the most part marine though some inhabit fresh water, and 

 which have a very wide distribution. A well-known British 

 species is the Common Bass {Morone labrax), which is much 

 like the Perch, but more slender in build and not so brilliantly 

 coloured, being bluish-grey above, gradually shading off to white 

 on the under surface. 



3. Sword-Fish Family. — The members of this family are 

 large fishes, mostly found in the open sea, and deriving their 

 name from the formidable sword-like weapon into which the 

 upper jaw is produced. The Common Sword- Fish {Xiphias 

 gladius) is sometimes taken in British seas, and occurs on both 

 sides of the Atlantic. Other species are found in the Atlantic 

 and Pacific. These fishes have become notorious from the fact 

 that their swords have been found broken off in the timbers of 

 ships, penetrating to a depth of as much as 22 inches (in a 

 specimen exhibited in the British Museum). The force with 

 which such blows have been given may be imagined. 



4. Dory Family. — This includes marine fishes of extra- 

 ordinary form, found in the East Atlantic, Mediterranean, and 

 the seas of Australia and New Zealand. The John Dory {Zeus 



faber) is not uncommonly found in British seas. The body 

 is much flattened, and with the head has a broad oval outline. 



VOL. I. 18 



