494 FI 



borne into colder latitudes, that they gradually come 

 nearer and nearer to the surface, and thus a stray fish 

 may accidentally be found on the shores of a tempe- 

 rate country, which is found only in the deep in 

 \varm latitudes. We may further suppose that those 

 strays will be found most frequently at or near the 

 point of confluence, where two opposite points meet, 

 or in the embayments of a shore, along which a cur- 

 rent sweeps when approaching the point of conflu- 

 ence. This seems to be the reason why there are 

 so many fishes on the south-west coast of England, 

 which are rarely, if ever, met with on any other part 

 of the British coast, and also why such fishes occur 

 (though more rarely) on the shores of the more 

 southerly of the western isles of Scotland, than on the 

 east coast. A similar cause appears to bring the 

 more northerly fishes to the north-west of Scotland, 

 and through between the Orkney and Shetland islands, 

 and so along the greater part of the east coast, in 

 numbers far greater than they are met with on the 

 west ; and if we inform ourselves well of the directions 

 in which those currents set, and the seasons in which 

 they act with the greatest force, we shall be in a con- 

 dition for understanding what may be called the 

 involuntary migrations of fishes. 



But notwithstanding those currents, it does not 

 appear that a very great number even of the surface 

 fishes follow them far out of their own seas. From 

 the islands which lie at the south point of America, 

 there is a counter current eastward produced there, 

 though it is probable that out at sea, clear of the 

 islands, the general current is westward. But not- 

 withstanding that there is thus apparently a facility 

 for the movement of fish both ways, it has not been 

 ascertained that there is a very extensive exchange 

 of fish in this way between the Atlantic and the 

 Pacific. So also there does not appear to be any 

 very great interchange between the Atlantic Ocean 

 by the Cape of Good Hope ; nor between the Indian 

 Ocean and the western Pacific, either to the south- 

 ward of Australia or through the passages between 

 that great island, and the south point of the Malay 

 peninsula, broken and interrupted as those passages 

 are by the numerous islands which lie between. 

 It would, however, require far more information than 

 we at present possess, or are likely ever to obtain, to 

 arrive at even the elements of those vast movements 

 of the ocean, and their effects upon the ocean's 

 inhabitants. 



The peculiar manner in which the tide circulates in 

 the Atlantic, and the portion of comparatively " slack 

 water," as it is technically called, which is the middle 

 of the space round which the current circulates in that 

 ocean, has no inconsiderable effect upon the distri- 

 bution of the fishes which inhabit it. In this central 

 space there is something analogous to a floating 

 island, only it consists entirely of aquatic plants, and 

 plants which are never at any time rooted at the 

 bottom, but which derive their nourishment by float- 

 ing in the water, in the same manner as the duck 

 weed (lemna) which mantles our stagnant pools and 

 ditches with green in the summer. This great float 

 of aquatic plants is known to sailors by the name of 

 the " gulf weed ;" and though it is unconnected with 

 the bottom, it covers a vast extent, and excepting 

 that it shifts a little northward and southward, sea- 

 sonally, the great mass of it remains pretty stationary. 

 This floating weed is a grand nursery for marine ani- 

 mals, not a few of which, especially the medusae, are 

 poisonous, and seem to impart that character to the 



SH. 



fish which feed upon them ; but still this sea-weed 

 forms a lodgment for very many of the floating mol- 

 lusca and Crustacea, and offers a convenient place oi 

 attachment for the spawn of the pelagic fish, the fry 

 from which again furnishes abundant food for othei 

 fishes, and also for aquatic birds. This weed does 

 not lie wholly quiescent ; for the boundaries arc 

 everywhere put in motion by the current, so that the 

 greater part of the mass may be said to revolve on a 

 sort of centre. There is a similar accumulation and 

 current, though from the position of the shores the 

 set of it is different, in the south Atlantic ; and though 

 the Pacific is too extensive, and has been too seldom 

 visited for enabling us to judge with accuracy of its 

 general phenomena, yet it is highly probable that 

 there are similar accumulations of sea-weed there 

 which are tenanted by similar classes of animals, and 

 visited by fish in the manner that has been described. 

 We cannot, however, enter farther into this most 

 interesting, but very extensive and exceedingly diffi- 

 cult subject ; and we have thrown together these few 

 particulars, more with a view of drawing the attention 

 of general readers to the wonders and the wealth of 

 the all-productive sea, than from any hope of commu- 

 nicating in a few pages, anything like substantial 

 information upon a subject, the full development of 

 which would form materials for the volumes of a 

 library. We shall close this desultory article with a 

 short outline of Cuvier's 



ARRANGEMENT OF FISHES. The great primary 

 division is into two sub-classes : osseous fishes, or 

 fishes strictly so called, which are justlyjregariled by 

 Cuvier as the typical ones ; and cartilaginous fishes, 

 or CHONDROPTERVGII, under which word some 

 account of their general characters will be found. 

 With regard to the osseous fishes, which are by far 

 the most numerous, they will hardly require a notice 

 in any separate article ; but the distinguishing cha- 

 racters of the divisions of them will be found under 

 the names referred to in the subsequent part of this 

 article. The two divisions now mentioned may be 

 considered as sub-classes ; and Cuvier divides each 

 sub- class into several orders, each order into families, 

 and each family into genera and specie*. Referring 

 to the article above named for the families of the car- 

 tilaginous fishes, which form only one order, and 

 admit of arrangement into three families, we shall 

 now consider the list of fishes, properly so called. 



These Cuvier arranges into six orders : Acanthn- 

 pterygii, Malacopteryga, of which there are three 

 orders, formed from the position of the abdominal 

 fins, Lophobranchii, and Plectognathi. Of the 

 first of these some notice has already been taken, 

 and reference made to the several sub-divisions in 

 the article ACANTHOPTERYGJI, to which the reader 

 is referred, so that we shall have to notice here only 

 the remaining five orders, which we can do more 

 effectively, and probably in much shorter space, than 

 if we were to devote a separate article to each. 



It will be perceived that this arrangement is not 

 founded on the same character or part of the or- 

 ganisation throughout all the orders ; and thus there 

 may appear to be an imperfection about it which is 

 not observable in the more artificial systems of others. 

 But, notwithstanding this, each order is founded upon 

 that structural character which is the most conspi- 

 cuous ; and, therefore, the arrangement is, perhaps, 

 the best which, in the present state of our know- 

 ledge, can be made, 



It would, perhaps, have given a little more neat- 



