42 BOARD OF AGRICULTURE. 



called, these organs are generally eight in number, four on each 

 side. Each of these consists of three parts, viz : a cartilaginous 

 or bony support and its convex side, and concave side. The 

 bony or cartilaginous support consists of a crooked bone or carti- 

 lage generally furnished with a joint. At its base it is united 

 with the bones of the tongue and above with those of the head. 

 At both extremities it is movable, and throughout flexible like a 

 rib. 



From its exterior or convex side issues the multitude of fibrils 

 or fleshy plumes before named closely connected with its base. 

 The internal or concave side next the mouth varies in appear- 

 ance. It is always more or less furnished with tubercles. It is 

 of a white color. 



In the cartilaginous fishes (Chondropterygii of some authors,) the 

 gills are not so perfect. They are fixed to partitions which serve 

 the purpose of the bony arches in bony fishes just described. 

 These partitions extend from the mouth to the gill openings and 

 vary in number in difi'erent genera. They are destitute of the 

 inner or concave white side, but the fibrils or fleshy plumes are 

 of the same structure with those on the convex side of the bony 

 fishes. — Ed. Ency. 



GuLAR — Pertaining to the throat or gills. 



H. 



Helicoid — A spiral curve ; (from helix winding, and eidos form.) 



HELiCAL^Spiral. 



Hermophrodite — Both sexes in one animal. This is alleged by Dr. 



Home to be the fact with the Lamprey Eel. 

 Heterocereal — Having upper lobe of the tail larger than the lower ; 



from heteros, different, and kerkos, tail. 

 HoLOCEPHALi — Solid heads ; from holos, whole or solid, and keph- 



ale head, the eighth order of fishes in some arrangements. 



The jaw bones and bones of the head united. 

 HoMocEREAL — Both lobcs of the tail equal. 



I. 



Ichthyology — The science which treats of the natural history of 

 fishes. From Greek iklhus fish, and logos discourse. 



Interradial — Between the rays. The membrane between the spines 

 or rays of the fin is said to be interradial. 



