CHAPTER II. 



GENERAL REMARKS ON FISH. 



Definition. — Origin and order in creation. — Natural mode of propagation. — 

 Habits as regards maternity. — Migration. — Vitality. — Exter'-al or- 

 gans. — Internal organization. — Ichthyology. 



A Fish, according to the definition of naturalists, is a 

 vertebrate animal with red blood, breathing through water 

 by means of branchiae, generally called gills. The term fish. 

 is frequently applied by unscientific persons, to animals not 

 of the ichthyic class, as in the case of the Whale, which is a 

 true mammal, but resembling the fish in many respects, 

 although its tail is placed horizontally instead of in an upright 

 position. Crustacea and Molluscs (Crabs, Lobsters, Oysters, 

 Clams, and Muscles), are also erroneously called "shell-fish." 



In the records of Creation, as shown by Paleontologists, 

 the remains of the earliest fishes appear in the upper Silurian 

 system, immediately beneath the Old Eed Sandstone. They 

 were the first vertebrate animals, and were cotemporaneous 

 with the earliest terrestrial vegetation. These fish were all 

 of one order, and are termed Placoids by Professor Agassiz. 

 They had internal cartilaginous frames, and an external 

 armature of plates, spines, and shagreen points. This order 

 has representatives at the present day, in the Sharks and Dog- 

 fish of our salt-water bays and inlets. Some of the ancient 

 Sharks had a mouth terminal at the snout, and not under- 

 neath as our man-eater, and instead of sharp incisors, the 



(39) 



