OE, PLAI1T TEACHING. 



81 



PISCES — FISHES. 



336. 



Fishes are divided into Jive great orders : — 1, Leptocardia, an order which includes only a 

 single fish, the Amphioxus lanceolatus, a little, slender, transparent creature, found on sandy 

 poasts in various parts of the world. 2, Cyclostomata, worm-like, without scales, destitute of 

 jaws, with mouths formed for sucking, Hags, Lampreys, etc. 3, Teleostia, having bony skele- 

 tons, possessing jaws, and usually teeth; the majority covered with scales of various forms ; 

 in some instances the body is covered with bony plates. This order includes a great majority 

 of species, and is arranged into six sub-orders. 4, Oanoidea, of which most of the examples 

 are fossiliferous* there being but few living species. 5, Seladria, cartilaginous, Sharks, 

 Rays, etc. 



[This arrangement combines the systems of Cuvier ana Agassiz, as blended by Muller.] 

 A A, corks, which support the upper line of the net, and keep it on a level with the surfaoe 

 of the water. B B, leads, which sink the lower line, and, acting in opposition to the corks, spread 

 the net in a vertical direction, and prevent the escape of the fish. 



Fishes are vertebrate animals , | in distinction from other animals 

 which means that they are dis- 1 that are invertebrate, or spineless. 

 tinguished by the possession of They inhabit water, and breathe 

 a jointed back-bone, or spine, 2, by means of branchice or gills, 3, 

 * Found in a fossil state. , instead of lungs ; they swim by 



4* 



