“The first of these series has for its character, that the palatine bones replace, in it, the bones of the upper jaw: moreover the whole of its structure has evident analogies, which we shall explain.
“It divides itself into three orders:
“The Cyclostomes, in which the jaws are soldered (soudées) into an immovable ring, and the bronchiæ are open in numerous holes.
“The Selacians, which have the bronchiæ like the preceding, but not the jaws.
“The Sturonians, in which the bronchiæ are open as usual by a slit furnished with an operculum.
“The second series, or that of ordinary fishes, offers me, in the first place, a primary division, into those of which the maxillary bone and the palatine arch are dovetailed (engrenés) to the skull. Of these I make an order of Pectognaths, divided into two families; the gymnodonts and the scleroderms.
“After these I have the fishes with complete jaws, but with bronchiæ which, instead of having the form of combs, as in all the others, have the form of a series of little tufts (houppes). Of these I again form an order, which I call Lophobranchs, which only includes one family. [428]
“There then remains an innumerable quantity of fishes, to which we can no longer apply any characters except those of the exterior organs of motion. After long examination, I have found that the least bad of these characters is, after all, that employed by Ray and Artedi, taken from the nature of the first rays of the dorsal and of the anal fin. Thus ordinary fishes are divided into Malacopterygians, of which all the rays are soft, except sometimes the first of the dorsal fin or the pectorals;—and Acanthopterygians, which have always the first portion of the dorsal, or of the first dorsal when there are two, supported by spinous rays, and in which the anal has also some such rays, and the ventrals, at least, each one.
“The former may be subdivided without inconvenience, according to their ventral fins, which are sometimes situate behind the abdomen, sometimes adherent to the apparatus of the shoulder, or, finally, are sometimes wanting altogether.
“We thus arrive at the three orders of Abdominal Malacopterygians, of Subbrachians, and of Apodes; each of which includes some natural families which we shall explain: the first, especially, is very numerous.