398 State 1>oakd oi-- Aouicultuki:, &c. 



Ordinary ossified fishes he divided into two orders : the 

 Cyloids, having scales consisting of simple layers with regu- 

 lar outlines, and the Cteuoids, having rough scales with 

 their edges serrated. There arc other differences between 

 these orders which we will not notice because this system of 

 classification has been shown to be an imperfect one, and is 

 not generally regarded by Naturalists. 



Dr. Theodore Gill, in his admirable treatise on Piscicul- 

 ture, with reference to American waters, divides all fishes 

 into four principal groups. All fishes having an ossified 

 skeleton, without any regard to the formation of the scales 

 or fins, or other difibrences in their organizations, he places 

 in a group by themselves and names them the Teleosts. The 

 second group corresponds to the Ganoids of Agassiz. The 

 third group he calls Elasmobranchia?, on account of the struc 

 ture of the gills. It includes both Sharks and Kays, and 

 corresponds with the Placoidians of Agassiz. The fourth 

 group comprises the Dermopter or Lampreys. 



The second, third, and also the fourth groups, we shall 

 pass by without notice. Most of them are represented in 

 American waters, and some of them furnish fresh water 

 types which are undoubtedly w^orthy the attention of the 

 pisciculturist. Many of these varieties are esteemed for 

 food in some countries, and could doubtless be successfully 

 cultivated and thrive in waters where other fishes would not 

 live. But I am not aware that any effort has been made to 

 domesticate them in our waters. The Teleosts furnish so 

 great a variety of forms, suited to so great a diversity of 

 waters, that it is unnecessary to go outside this group to find 

 ample material to occupy our attention. We have already 



