E T A C E A. 



770 



vital function?, and the mode of production of land 

 animals, while in external shape and in habitat they 

 resemble fishes. Their blood is warm, warmer than 

 that of many of the terrestrial mammalia. They 

 have a double circulation ; they breathe the free air 

 by means of lungs ; and they bring forth their yonni: 

 and .'tickle them with mi'lk. Their bones, their 

 muscles, in short, all the parts of their bodies, when we 

 come to examine them, are in their textures really 

 the parts of mammalia, only their shape has some 

 resemblance to that, of the fishes. 



In their leading characters they arc mammalia, 

 altogether destitute of hind feet, or indeed any lateral 

 appendages to their bodies, excepting 1 short fore legs, 

 which are formed into swimming paws. Their ver- 

 tebral column is continued beyond the cavity of the 

 body in a long and thick tail, which terminates in a 

 very powerful iin ; but this iin is very different, both 

 in form and texture, from the fins of fishes. The 

 muscles by which it is put. in motion do not consist 

 of a series of transverse Hakes superposed upon each 

 other, as is the case in fishes. They are longitudinal 

 fibrous muscles like those of the land mammalia ; 

 and when, as is the case in some of the muscles of 

 those, they are divided by septa, these are always 

 (artilasnnoMs, and the fibres are iinnly united to them. 

 These muscles have distinct, tendons ; and thus the 

 single fin in which the tail terminates has much more 

 ranu'e, varietv, and even power of motion, than the 

 caudal fin (if a fi>h. The natural position of the lobes 

 of this fin is ii-ivi/.ont.al, while that of ail fishes is ver- 

 ticil, though then- are some fishes which swim on 

 their sides, and those have the appearance of a hori- 

 :1 fin on the tail. It will be always found in 

 fishes, however, that, when they swim with the 

 tail thus apparently boir/.ontal the Cavity of the body 

 is on one side ; and though their necks are twisted 

 so that both the eyes are on one side of the head in 

 appearance, yet this twist is a permanent one ; and 

 they have no rotatory or twisting motion of the tail, 

 which is always moved by the flexure of the joints of 

 the vertebra: only. 



The cetaeea, on the other hand, have very con- 

 siderable motion in that organ ; they can twUt it to 

 a great number of angles ; and the portion of it 

 nearest the iin has also much more motion than that 

 part of the tail of any ordinary fish ; they can bend 

 it upwards, downwards, laterally, or obliquely. 



Their brain is larger in proportion and much better 

 developed than the brain of ii.-hes ; their eyes have 

 expression, which is not the case with those of any 

 fish ; and though they have very small openings, and 

 no external production of ears, they have them tole- 

 rably well formed in the interior, and possess a dis- 

 tinct sense of hearing in the air, which is not, accord- 

 ing to appearances, possessed by any fish. 



(Generally speaking, the cetacca are large animals, 

 and some of them far exceed in their dimensions any 

 other mi'inhcrs of the animal kingdom ; but there arc 

 considerable differences annum 4 them in this respect. 

 and in other respects they <lii!'er much more. We 

 shall point, out the diifcivnces upon which the divisions 

 and ?ubdi\ision.3 of the order are founded; but the 

 animals, taken altogether, are so peculiar, and have in 

 common language been so much associated with 

 fi-hcs, that it may be proper first of all to take a slight 

 structural view of the whale. 



Anntomicdl Structure. The external form of the 

 cetaeea is not made out by that of the skeleton, as in 



those mammalia which have motion upon land : it is 

 even much inferior in this respect to that of the seals 

 and walruses, especially the former. The bones are 

 of a loose and coarse texture, greatly inferior both in 

 specific gravity and in strength to those of land ani- 

 mals. These fibres, in the larger bones such as the 

 jaws and ribs, are easily separated ; and none of them 

 have any medullary tube or marrow in them like the 

 round bones of land mammalia. They are, however, 

 in most of the species very copiously supplied with 

 oil in all these pores or openings, which supports 

 their loose and spongy fibres. 



This character of the texture of the bones is a very 

 marked one, and a very remarkable instance of adap- 

 tation. The bones of a whale when recent and satu- 

 rated with oil are not much, if anything, heavier than 

 water; and as the whale skeleton is every where 

 defended from the shock even of the water, by the 

 mass of muscles and fat which make up the body to 

 its fish-like shape, there is nothing that can very 

 much injure their loose and comparatively weak 

 bones. So completely indeed is the whale always 

 can led upon elastic springs in its liquid clement, that 

 to have given it the same compact bones as animals 

 which move upon and come in contact with solids, 

 would have been only loading- it with an unnecessary 

 weight of salts of lime. 



When the whales are seen in entire carcass, they 

 seem to have hardly any neck ; but when the skele- 

 ton is examined, they are found to have the same 

 number of vertebra, seven, which is common to all 

 mammalia, to the giraii'e and the camel, as well as to 

 the porpoise and the whale. The cetaeea have not, 

 however, the same necessity for turning or otherwise 

 moving the head as land animals have, because they 

 can turn the whole body in the water with much 

 more ease than a much smaller animal standing upon 

 feet, and thus having its weight supported at most on 

 four points, can do upon land ; and therefore they 

 have exceedingly little motion of the vertebra 1 of 

 the neck. The dolphins and porpoises have the two 

 vertcbne nearest the head anchylosed, or soldered 

 iier; while the spermaceti whales, which are 

 remarkable for the enormous size of their head, have 

 the one next the back united in the same manner, so 

 that they have hardly any motion of the neck. 



The dorsal vertebra 1 , and with them the number of 

 . ary much in the different species, some Inning 

 .ay as thirteen ribs on each side, and others not 

 more than eight. Posterior to the dorsal vert. 

 tin re cannot be the same distinction made as in ani- 

 mals which have a pelvis and hind legs ; but some of 

 them have the vertebra? of this part very numerous. 

 A .\ e iind here one gradation from land mammalia 

 through the seals to the cetaeea. Seals have the 

 hind legs and tail united so as to form a sort of iin or 

 swimming flap, while in cetaeea the whole organi>a- 

 tion of the body, posterior to the ribs, is concentrated 

 into the action of the tail. Analogically, therefore, 

 we may consider the tail of a whale as combining the 

 energies of a tail and pair of feet not merely soldered 

 together, but actually formed into a single organ ; and 

 the length of spine and number and power of nin 

 which belong to this organ make it one of great effi- 

 cacy ; and as the proboscis of the elephant has, in 

 reality, though a clumsy thing 1 in appearance, more 

 mechanical power and working in it than many hands ; 

 so the tail of a whale, huge and unwieldy as it seems, 

 is far more curious in its action, and also far more 



