424 V E U T E r. K A T A. 



ti'miK->t,niiil with tlioir divdixi's aii<l (ra\vliiii,'-iR'ls rakiiiir the rout^h bottoms of those rocky coasts, 

 uikI ilnnviiiij thi-uoe tuiU)t, sole, bleak, ray, liiijjj, aiwl a nuiltitiide of' otlicr uncouth but still coveted 

 monsters of the deep— these all follow a profession which not only atiords support to the body, 

 but feeds rude spirits with a tierce delight. 



The importance of fishes as a source of national wealth, renders their geographical distribu- 

 tion a matter of interest and importance. This seems to be determined by nearly the same laws 

 JK those which regulate that of othi-r acpiatic animals. Climate, composition of the element in 

 wiii.h they livi — whether salt, brackish, or fresli — and conformation of the sea or river-bed, on 

 which the depth of water depends, are the chief controlling influences. The leading distinctions of 

 form and color between fishes of tropical and those of temperate regions, evince the influence of 

 climate ; the fact of the fisheries for certain species commonly used for food being invariably con- 

 ducted in tleep water, while others can only be maintained among shallows, shows the influence of 

 depth ; the fact pointed out by Sir John Richardson that the seas, marked by ranges of land or 

 reefs extending for great distances under the same climatic parallel, arc peopled by the same species 

 of fishes, is an instance of the action of the combined influences of climate and depth. The dis- 

 tinetness as to genera and species of the greater number of river and lake fish from those inhab- 

 iting the sea, depends on the second of the three great influences enumerated — that of the com- 

 position of the element in which they live. Great depths cut off" the range of species even when 

 climatic conditions are similar. Hence the fishes of the coast of the United States are for the 

 most part distinct from those on the European side of the Atlantic. Some fishes have very 

 limited ranges in depth compared with others, and, generally speaking, it may be assumed that 

 those having the greatest vertical range — that is, range in depth — have also the widest horizontal 

 extension, a fact depending on the capacity of snch species for living under a greater variety of 

 conditions. Barriers of land, as chains of mountains, determining the courses of rivers, are often 

 the boundaries between two distinct specific assemblages of fresh-water fish, and in like manner 

 a very narrow strip of land may divide two very distinct marine fiiunas. The distribution of 

 marine vegetables, affecting the distribution of numerous marine Invcrtebrata which feed on 

 those vegetables, and in their turn serve to furnish food for fishes, will materially aftect the dis- 

 tribution of many species of the latter. So also will the presence of currents, and even the 

 agency of man, assisting often unintentionally in the conveyance of ova from one country to 

 another. Distant regions, presenting similar conditions, such as the arctic and antarctic seas, 

 are inhabited by species representative yet not identical, and presenting a general aspect very 

 similar, depending on characters of form and color, <fcc. It is probable also that the fishes inhab- 

 iting the greater depths of tropical seas resemble those of temperate climes, and that those of the 

 latter in like manner approach arctic forms. 



Considering the immense number of fishes, and the almost endless diversity of their forms and 

 their characteristics, it is not surprising that they should present great difliiculties in their classi- 

 fication. The arrangement of Cuvier, which we have given in outline in the Introduction to 

 this work, was the leading one for a time, but it has been modified by more recent naturalists. 

 As we can only give a very brief description of prominent species, we shall notice them under 

 five orders, as follows : the Selachia^ the Ganoidea, the Teleostea, the Cyclostomata, and the 

 Leptocardia, 



. ORDER 1. SELACHIA. 



This order derives its name from the Greek selackos, a shark, and includes the Sharks and 

 Hai/s, and corresponds with the typical species of Cuvier's Chondropteryc/ious fishes. The 

 skeleton is entirely of a cartilaginous nature ; the teeth variable, being in the Sharks, which are 

 the most active and predacious members of the order, exceedingly sharp, compressed, and occa- 

 sionally serrated at the edge ; in the Rays they sometimes exhibit the same trenchant character; 

 in other cases they are arranged in mosaic, and in still others the teeth form broad pavement- 

 like plates. They are never inserted into the jaws, but are retained in their position by the 

 strong skin of the gums. The fins are variously disposed ; the skin is sometimes quite naked. 



