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C E T A C E A. 



the dolphin by the Dutch and sonic other nations. 

 It is a true fish (the coryphene) and not a warm- 

 blooded animal as the real dolphins are. It is pro- 

 bable that the ancients did not always mean the 

 coryphene when they spake of the dolphin, though 

 that fish was certainly the dolphin of the Mediter- 

 ranean Arioits dolphin. But when Juvenal, in his 

 tenth Satire, makes use of the simile of the dolphin 

 and the whale, in a sense not very dissimilar to that 

 of the fable of the frog and the ox, it is possible that 

 he may have meant the warm-blooded dolphin : 

 " Quanto delphinus balteua Brittanica major." 



The dolphins have not the enormous head which 

 is characteristic of the whales ; and on that account 

 they are more shapely animals. Their jaws are 

 lengthened, and both are furnished with conical teeth, 

 placed in an even row, but varying in number with 

 the species. The blow-holes pass the upper jaw in 

 two separate apertures, but the openings are conjoined 

 into one externally, which is on the top of the head, 

 and of a crescent shape. The eyes are placed near 

 the angle of the mouth. All the species have dorsal 

 fins, with the exception of one, and these fins are 

 often of vast length, appearing like the sail of a boat 

 as the animals swim, or rather tumble along through 

 the water ; for their march, which is much more rapid 

 than it seems, is made by a series of leaps, at the 

 middle of each of which the fin, and indeed the 

 greater part of the body, is seen above the water, 

 while, at the beginning and end of the leap, the whole 

 disappears. 



This is the mode of swimming in all the cetacea ; 

 and it is easy to see, Irbm the formation of the tail, 

 the most powerful organ of motion in them all, that 

 this must be the case. Their action, like that of land 

 mammalia, is in the vertical plane, while the most 

 powerful action of fishes is in the horizontal. Their 

 tails strike upward and downward, and those of fishes 

 strike laterally ; the resistance to the stroke upwards 

 is less than to the stroke downwards, because the 

 pressure of the water increases with the depth ; and 

 thus when the cetaceous animals make great exertions 

 in swimming, they always to a considerable extent 

 work themselves up to the surface. This agrees with 

 their economy as animals that breathe the free air ; 

 as it gives them the opportunity of breathing at the 

 top of each of their leaps, without any other muscular 

 exertion than that which is required for their progres- 

 sive motion through the water. We know by expe- 

 rience that the respiration of all animals requires to 

 be increased in the proportion of the exertion which 

 they make ; and it is a beautiful instance of adapta- 

 tion to find that those air-breathing animals, which 

 find their food in and generally inhabit the water, 

 come naturally upon that element in which they 

 breathe, whenever greater exertion renders more fre- 

 quent respiration necessary. 



Fishes again, which breathe water, have no ten- 

 dency from the mere action of swimming either to 

 rise or to descend, their tails strike the water right 

 and left, and of course they strike against exactly an 

 equal pressure both ways ; and thus, when they either 

 rise or descend in the course of their progress, they 

 do it by an additional effort, and they are fatigued by 

 it, and also have their peculiar kind of respiration 

 impeded rather than assisted by it. 



This can be very well observed of the common 

 porpoise and the salmon, in the estuaries of the salmon 

 rivers. The porpoise is very fond of salmon, and 



pursues them with great assiduity as they ascend the 

 rivers. This is best seen, when it clears up after a 

 heavy summer rain, which has brought a good deal 

 of "fresh" into the estuary. The salmon always 

 swim upon the " fresh," whether on account of its 

 being there an additional supply of food, or for some 

 other physiological cause, is not very clearly known ; 

 but any one who has paid any attention to the habits 

 of salmon must be aware of the fact. 



The salmon hold on their straight course, not far 

 from the surface, for, as we have said, the}' swim 

 upon, that is, they swim to meet the fresh ; but while 

 they are able to keep at a safe distance from the pur- 

 suing enemy, they do not appear above water. The 

 porpoises tumble along, in the manner above de- 

 scribed, not only showing the fin, but, in their 

 eagerness to catch their prey, springing partly, or 

 even altogether, out of the water. This is, by the 

 way, far from the worst time for striking porpoises 

 with the harpoon, or even with the spear, if they uiv 

 very eager in the chase, and they generally arc so, 

 and also not singly, but in packs. 



At length the salmon begin to get fatigued and 

 exhausted ; for there is nothing to renovate them in 

 the same way that the ascent to the air renovates the 

 porpoises ; and when they are all but in the formi- 

 dable jaws of the enemy, they leap into the air ; but 

 that is a means of fatigue to them, and not of relief : 

 it is only another tumble forward on the part of the 

 porpoisu, and the salmon falls exhausted into its 

 mouth. If both animals are in numbers, on a summer 

 evening, when the sun is low, and the sky has just 

 cleared of the rain, this chace is a very beautiful 

 sight. The scales of the salmon show prismatic co- 

 lours, and, as their leaps are taken with great rapidity, 

 they seem as if they were little rainbows, rising 

 momentarily out of the water. We shall now notice 

 a few of the leading species of dolphins. 



Delfj/iinus pkoccsiia (the common porpoise). This 

 species, the common name of which in most European 

 languages means "sea-hog," is the most abundant and 

 the best known. It is plentiful in all the European 

 seas, and especially so upon the coast of North 

 America. Though a thick and apparently unwieldy 

 animal, it is exceedingly active in the water, and even 

 playful, frisking and even gamboling about, as if fond 

 of amusement. There is a good deal of " speculation" 

 in its eye, as compared with the eyes of fishes ; and 

 it shows an attachment to its kind, of which there is 

 no known instance among the cold-blooded inhabi- 

 tants of the deep. Many of the fishes assemble in 

 shoals, but there does not appear to be any principle 

 of society among them ; and there are at least many 

 of the species, in which the large ones prey on the 

 little as readily as on any other kind of food ; but it 

 does not appear that any of the cetacea are cannibals ; 

 and the porpoises certainly imagine each other as 

 members of the same society. 



They accompany all the smaller species of shoaling 

 fish upon their migrations ; and where these are abun- 

 dant, the porpoises often appear in very numerous 

 packs, darkening the surface of the sea as they 

 display their fins, and the upper parts of their bodies. 

 When they are more playful than common, the sailors 

 usually regard it as a sign of bad weather ; and it is 

 probable that they are correct. The storm at sea is 

 a time of want for many of the fishes, more especially 

 those that find their food near the surface ; and we 

 may suppose that, according to the general law of 



