[2451] The pleuronectes in general, Cuvier says, have the two eyes situate on the same side of the body. The turbot has them on the left side, and lies on the sand on the right side, while the plaice or the flounder has the eyes on the right, and lies on the left side—the reverse of what Pliny says.
[2452] Aristotle, Hist. Anim. B. i. c. 6.
[2453] By this Pliny means, Cuvier says, only the symmetrical fins, or pairs of fins, the pectoral namely, which are in place of arms, and the ventral, which are instead of feet; of which, in fact, no fish has more than two pairs. Pliny does not include in this statement the dorsal, anal, and pectoral fins.
[2454] Eels and congers, for instance, which have but one pair.
[2455] Murænæ and lampreys.
[2456] See B. iii. c. 17.
[2457] Cuvier thinks that there can be no question that he is speaking here of some mollusc or crustaceous animal.
[2458] Murænæ, like eels, have gills, but the orifice, Cuvier says, is much smaller than in the eel, and the opercula, under the skin, are so small as to be hardly perceptible; indeed, so much so, that modern naturalists, Lacepède, for instance, have denied the fact of their existence.
[2459] Aristotle, De Part. Anim. B. iv. c. 13, and Hist. Anim. B. i. c. 6.
[2460] Or sting-ray. On the contrary, Cuvier says, the pastinaca, more than any other ray, has large pectoral fins, horizontally placed; but they adhere so closely to the body that they do not appear to be fins, unless closely examined.