F I S H. 



uith the mechanical structure of a fish : and that 

 however a fish may be able to bend itself laterally, 

 or even obliquely, there is no provision in the mus- 

 cular structure of any one fish, by means of which 

 it is able to bend the spinal column cither upwards 

 or downwards. The bending of flat fish toward the 

 pale coloured side especially, must not be considered 

 as an exception to this ; for the flat fishes, as we have 

 said, swim 011 their side; and the finned margins of 

 their disc are as truly the middle of the back and 

 middle of the belly marking the terminations of the 

 mesial plane, as if they swam with that plane in the 

 vertical direction and not in the horizontal. These 

 few remarks must suffice in the meantime, for the 

 various motions of the different fishes are so curious, 

 and involve so many points in mechanics, that if we 

 were to allow ourselves to get entangled in the 

 details, there would really be no end. The subject 

 is simple however, and as, in addition to this, it is 

 highly instructive as a mechanical subject, it is emi- 

 nently deserving of every reader's most careful atten- 

 tion and most diligent study. 



Organs of adhesion. The consideration of this 

 branch will not detain us long. Fishes, generally 

 speaking, have no apparatus, excepting the mouth, 

 by means of which they can take hold of any one 

 substance, and therefore, excepting in so far as they 

 can counteract by means of their swimming apparatus, 

 they may be said to be at the mercy of the waves. 

 That apparatus is, however, so efficient ; and the waves 

 produced by surface agitations reach to so very 

 small depths in the sea, that, generally speaking, the 

 fishes may be said to be perfectly independent of 

 them, except some of the lighter surface fishes, and 

 the small fry which are occasionally caught in storms, 

 and stranded on the shores in countless numbers. 



There are, however, countless fishes which, from 

 the peculiar places in which they seek their food, 

 and the peculiarity of that food itself, have to hold 

 on in the ftrength of currents, which would be too 

 much for the fins of even the strongest and best 

 formed of the finny tribes ; and those species to which 

 nature has assigned this habit, have of course received 

 an adequate means of adapting themselves to it. 

 The apparatus used for this purpose is a sucker, or 

 cartilaginous disc, which this fish can apply so firmly 

 to the surface of any solid object, fixed or floating, as 

 that no action of the water can detach it. This 

 sucker, when it is a mere means of stability, is placed 

 either on the head or the thorax. In the remora, 

 which has been so long celebrated, and of which so 

 many ridiculous stories have been told, and of which 

 as a genus, some account will be found in the article 

 ECHENIS, the sucker is of an oval form, and consists 

 of transverse rows of cartilaginous plates connected 

 by one edge to the surface of the head, and in the 

 other edge free, and finely pectinated. A longitu- 

 dinal partition divides the plates in the middle of the 

 head, and in the spaces between the plates, and on 

 each side of the partition, a row ot fleshy tubercles may 

 be observed. In the cyclopteri this organ is of a circu- 

 lar form, and consists of numerous soft papillae. It 

 is situated on the thorax. Instead of a separate 

 organ of adhesion, the ventral fins in the goby are 

 united, and are capable of adhering to rocks and 

 stones, while in the lamprey the mouth contracts and 

 acts as a sucker. All the species which have suckers 

 of this kind for the purposes of mere adhesion, 

 whether those suckers are placed on the upper or the 



under part of the body, belong to the eubbrachian 

 family of the soft-finned fishes. They are generally, 

 if not all, fishes of feeble powers ; but the sucker 

 enables them to adhere to rocks over or under them, 

 according as it is at the top of the head or under the 

 body ; and while they so adhere, secure against the 

 current, they are enabled to capture for their sub- 

 sistence the fry of fishes, and other small animals 

 which the current carries along. Of course they are 

 not found in the placid waters, where this apparatus 

 would be of no service to them, but chiefly in 

 passages among rocks, through which currents set 

 with much rapidity. 



Some of the cartilaginous fishes are also furnished 

 with suckers ; but the suckers which they possess 

 are placed on another part of the body ; and gene- 

 rally speaking, calculated for other purposes. They 

 are on the mouth, as in the lamprey, the pride, the 

 hag, and some varieties ; and though these are found 

 at least in some of the species, occasionally adhering 

 to stones with great firmness, yet the principal use 

 of the sucker appears to consist in enabling them to 

 extract their subsistence from the bodies of animals 

 to which they adhere ; and among them the hag, 

 which is in appearance little else than a gelatinous 

 sac, often sucks the substance of cod and other fishes 

 while they are fast on the hooks of the fisherman's 

 lines. See the article MYXINE. 



Respiration and Circulation. Both the organs and 

 the process in these have been mentioned in the 

 general preliminary remark?, so that it remains only 

 to notice the differences which are found in different 

 kinds of fishes. The respiratory organs are perhaps 

 to be regarded as the most perfect and typical of a 

 fish, when the gills are distinct upon the bony arches 

 and face, and the gill openings ample and furnished 

 with the most complete apparatus in the gill-lid. 

 This part of the apparatus is sometimes wanting, but 

 the gills themselves never are. When it is most 

 complete, then is the gill-lid itself placed on each 

 side of the head immediately behind the eye. articu- 

 lated to the bones of the head, and shutting in the 

 rear against the bony side of the shoulder, especially 

 the large bone which answers to the humerus ; and 

 the lower extremities of both of which are riveted 

 by a fleshy cartilage, and a similar substance ties 

 them tOjthe os hyoides; thus uniting the parts against 

 which the gill-lids close with those to which both 

 they and the gills are attached. This gill-lid is, in 

 its external texture, either scaly, or membranous, or 

 bony, and it is sometimes furnished with one or more 

 hard tubercles or spines. Internally, it always con. 

 sists of thin and flexible plates of bone, composed of 

 a greater or small number of pieces in different 

 places. When it consists of many, the one next the 

 head, which is often double, is called the pre-ojyerculc, 

 the one behind that, toward the upper part, the opcr- 

 cji/e, below that there is the subopercule, and between 

 this last a.id the extremity of the os hyaides, the inter- 

 opercule. The posterior margin of the gill-lid, in- 

 cluding under that name all the pieces above enume- 

 rated, or as many of them as may exist in the species, 

 is variously toothed, though sometimes it is plain. 

 In the greater number of fishes it is furnished with a 

 fin-like appendage, called the gill-flap, which is sup- 

 posed to contribute in some way or other to the 

 action of the lid itself, and consequently to the 

 breathing of the fish. 



Count Lacepede founded a good deal of the clas- 



