FIREWORKS.— FISHES. 53 



Till'age. — The operation, practice, or art of tilling or pre- 

 pariiip; land for seed, and keeping the ground in a state 

 favorable for the growth of crops. 



Tongue-grafting. — A mode of grafting by inserting the end 

 of a scion in a particular manner. 



Top'-dressing. — A dressing of manure laid on the surface of 

 land. 



Top'iary-Work. — The fanciful form sometimes given, by cut- 

 ting and trimming, to arbors and thickets, trees and 

 hedges. 



Trencll'ing. — The preparation of soils by digging two or more 

 spades deep and exposing the soil. 



\¥arp. — A slimy substance deposited on land by marine tides, 

 by which a rich alluvial soil is formed. 



Win'nowing. — The operation of separating and driving off 

 the cliatt" from grain by means of wind. 



FIREWORKS. 



Pyrotechnics (Gr. p(«r, fire, and techne, an art). — The art of 

 making fireworks, or the science which teaches the manage- 

 ment and application of fire in its various operations, par- 

 ticularly in making rockets and other artificial fireworks. 



FISHES. 



Ichthyol'ogy (Gr. ichthus, a fish, and lorjos, a discourse). — The 

 science of fishes, or that part of zoology which treats of 

 fishes, their structure, habits, etc. 



The class has been divided into five orders, as follows : 



1. Sela'chii. ^Fishes with cartilaginous skeletons and five 

 or more gill-openings on each side, including the sharks 

 and rays. 



2. Ganoid'ei. — Fishes whose bodies are covered with hard 

 plates, including the sturgeon, etc. 



3. Teleos'tei. — Bony fishes. 



4. Cyclos'tomi. — Boneless fishes, including the lampreys 

 and other irenera. 



5. Leptocar'dii. — The amphioxus or lancelot. 



The order Tdcoatci is divided into the following sub-orders : 

 A. Plectog'nathi. — Those in which the bones of the upper 

 jaw and face are firmly attached to, or amalgamated with, 



