2 " NATURAL HISTORY. 



groups of animals which have already been described. The slender form of the Lamprey or Eel 

 contrasts with the expanded body of the Turbot or Plaice ; the short deep form of the Sun-fish is 

 unlike the broad, flattened, and long-tailed Skate ; the Sea Horses, when attached by their prehensile 

 tails, at first sight present none of the familiar characteristics of fishes ; the Flying-fish, which have 

 the fins so expanded as to serve some of the purposes of wings, present a remarkable contrast to 

 the spheroidal spiny body of the Globe-fish ; while the Hammer-headed Shark exhibits a form of 

 body in some respects more singular still. When we turn to details of proportion and structure, 

 and contrast the shapes of the head or of the tail, the variety among fishes is altogether exuberant. 

 Ill the covering of the body there is not so much scope for variation, for although some are con- 

 tained in a box of bony plates, or mailed with armour far heavier in proportion than that of the 

 knights of old, and some fishes have, on the other hand, scales so delicate that they are detected 

 with difficulty, yet by far the larger number of living fishes are clothed with soft scales, which impart 

 to them much of their beauty, and differ in little more than size and details of ornament in the 

 multitudinous genera. But beyond the claims upon our attention which the external forms of 

 fishes certainly make, an interest of a far higher kind is always aroused by their wonderful habits. 

 Here we find the herbivorous and carnivorous types of the land reproduced. Many fishes like 

 the Sword-fish, for instance seem specially moulded into shape for purposes of slaughter: many 

 fishes, like most of those with transversely-expanded bodies, pass their lives more or less quietly on 

 the bottom of the sea, and simulate the sand they rest upon; other groups, like Eels, dive into 

 the sand as though it were their natural home ; others, again, like the Gurnards, crawl with their 

 appendages at the sides of the head, almost like some of the Crabs, when they are not freely 

 swimming. Some fishes, like the Sturgeon, find their home indifferently in fresh or salt water ; 

 several, like the Salmon, require to descend annually from the river to the sea. Multitudes of 

 fishes travel in fellowship year by year over a large portion of the ocean, a few fresh-water fishes 

 journey over land, and one or two are sometimes found roosting like birds in the branches of trees. 



The industries which fishes have contributed to develop have given this group of animals an 

 importance scarcely second to mammals and birds. No small proportion of the food of mankind 

 is obtained by the fleets of fishing-boats around the coasts, and by the humbler nets, and snares, 

 and lines with which fishes are captured in rivers and lakes. The use of fish for manure is of 

 ancient date ; the capture of fishes for the manufacture of medicinal and other oils, gelatine, 

 and isinglass is carried on on a large scale ; the skins of Sharks have always been valued for the 

 decoration of some kinds of military weapons no less than by the cabinet-maker for their rasping 

 properties. Much of the artificial jewellery, which resembles pearls so closely as almost to equal 

 the natural production of the sea-shell Avicula margaritifera, owes its beauty to a preparation 

 from the scales of the Bleak and other fishes. 



The fecundity of fishes far surpasses that of any other group of vertebrated animals. The eggs 

 laid by a single fish sometimes may be counted by millions. They are almost always small as 

 may be seen in the ordinary hard roe of the fishes which are eaten and are frequently minute. 

 They pass through no metamorphosis, as do the young in their development among the higher group 

 named Amphibia ; but occasionally fishes are viviparous, and then the young are retained within 

 the body of the parent until they have reached a relatively large size. Fishes furnish us with the 

 smallest examples of the Vertebrates which are known, and also with some of -the biggest forms, 

 though they never make any approach to the giant length of the larger Whales. By far the greater 

 number of fishes are of relatively small size. 



As with mammals and birds, the great majority of fishes are characterised by comparatively 

 dull colours, which probably serve to conceal them from enemies, and have been developed as a means 

 of enabling them to mimic the aspects of the regions of sea and river which they frequent. But 

 all are not so simply decorated. The brilliant colours of the gold and silver and violet Carp are 

 well known. Many fishes are striped and spotted, or burnished with colours which almost rival 

 those of gaudy birds, and it would be difficult to name a tint which could not be matched among 

 some representatives of the fish class. Too little, however, is known of the habits and ways of life 

 of these highly-coloured fishes to enable us to judge how far they are an advantage to the species, 

 which are thus characterised. 



