Balænæ have the mouth2234 in the forehead; and hence it is that, as they swim on the surface of the water, they discharge vast showers of water in the air. (7.) It is universally agreed, however, that they respire, as do a very few other animals2235 in the sea, which have lungs among the internal viscera; for without lungs it is generally supposed that no animal can breathe. Those, too, who are of this opinion are of opinion also that no fishes that have gills are so constituted as to inhale and exhale alternately, nor, in fact, many other kinds of animals even, which are entirely destitute of gills. This, I find, was the opinion of Aristotle,2236 who, by his learned researches2237 on the subject, has induced many others to be of the same way of thinking. I shall not, however, conceal the fact, that I for one do not by any means at once subscribe to this opinion, for it is very possible, if such be the will of Nature, that there may be other organs2238 fitted for the purposes of respiration, and acting in the place of lungs; just as in many animals a different liquid altogether takes the place of blood.2239 And who, in fact, can find any ground for surprise that the breath of life can penetrate the waters of the deep, when he sees that it is even exhaled2240 from them? and when we find, too, that it can even enter the very depths of the earth, an element of so much greater density, a thing that is proved by the case of animals which always live under ground, the mole for instance? There are other weighty reasons as well, which induce me to be of opinion that all aquatic animals respire, conformably to their natural organization; for, in the first place, there has been often remarked in fishes a certain degree of anhelation during the heat of summer, and at other times again, a kind of leisurely gaping,2241 as it were. And then, besides, we have the admission of those who are of the contrary opinion, that fishes do sleep; but what possibility is there of sleeping2242 without respiring as well? And again, we see their breath disengaged in bubbles which rise to the water’s surface, and the influence too of the moon makes even the very shells2243 grow in bulk.

But the most convincing reason of all is, the undoubted fact that fishes have the power of hearing2244 and of smelling, two senses for the operation of both of which the air is a necessary vehicle; for by smell we understand nothing else than the air being charged with certain particles.2245 However, let every person form his own opinion on these subjects, just in such way as he may think best.

Neither the balæna nor the dolphin has any gills.2246 Both of these animals respire2247 through vent-holes, which communicate with the lungs; in the balæna they are on the forehead,2248 and in the dolphin on the back. Sea-calves, too, which we call “phocæ,”2249 breathe and sleep upon dry land—sea-tortoises also,2250 of which we shall have more to say hereafter.