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Show 298 PISCES. very, blackish and olive on the back; first dorsal very distinct from the second; two large separated teeth on the upper part of the maxillary ring. Inhabits rivers, &c. P. planeri, Bl.; Sucet, &c.; Gesner, 705. (Small River Lam· prey.) From eight to ten inches long; teeth and colours of the fluvialis; the two dorsals contiguous or united. Rivers, &c.(l) MYXINE, Lin. But a single tooth on the upper part of the maxillary ring, which is altogether membranous; lateral dentations of the tongue strong, and arranged in two rows on each side, so that the jaws of these fishes seem to be lateral like those of Insects or the Nereides, which in· duced Linnreus to place them in the class of Vermes; the rest of their organization, however, is analogous to that of the Lampreys:(2) the tongue also acts like a piston, and the spine of the back is in the form of a cord. The mouth is circular and surrounded with eight cirri; in its upper margin is a spiracle which communicates with its interior. The body is cylindrical, and furnished behind with a fin that surrounds the tail. The intestine is simple and straight, but wide and plaited internally; the liver bilobate. There are no vestiges of eyes. The eggs become large. These singular animals pour out such an abundance of mucus through the pores of their lateral line, that the water of the vases in which they are kept seems to be converted into a jelly. They attack and pierce other fishes like the Lampreys. They are subdivided according to the external orifices of their branchire. In HEPTATREMus, Dumer. There are still seven holes on each side, as in the Lampreys. But a single species is known, Gastrobranche dombey, Lacep., I, xxiii, 1; Petromyzon cirrhatus, Forster; Bl., Schn., p. 532; from the South Seas.(3) 1 ) N.D. The figure of the Planeri, Bl., 78, 3, is a young jluvialis. I also think that the Petrom. sucet, Lacep., II, i, 3;-Sept-oeil, IV, xv, 1;-Noir, 1b,,2, are mere varieties of the planeri: but the fig. I, ii, 1, under the name of !Amproyon, Petrom. branchialis, represents a peculiar species of this genus, and not an Ammocretes. I see no difference between the Petrom. argenteu8, Bl., 415, 2, and the jluviali8. (2) See the Memoir of Abildgaart, Trans. Soc. Nat. Berlin, vol. X, P· 193. (3) See the Memoir of Sir Ev. Home, Phil. Trans., 1815. CHONDROPTERYGII BRANCHIIS FIXIS. 299 GASTROBRANOHus, Bl. The in·t ervals · ohf the branchire, instead of having se parat e I· ssues, co·m mum· cate Wd' it · a common canal on each side ' eac h of wh 1' c h ter· m.m ates m a Istmct hole situated under the heart, near th e fi rst th1rd of the whole length. But a single species is known, Myxine glutinoaa L . G t b h , ., as ro-ranc us crecus, Bl., 413; the Glutinous Hag From th A · 0 · e rchc cean. AMMOO<ETEs, Dumer. All the parts which should constitute the skeleton, so soft and membranous that they are hardly entitled to the appellation of bone. The ~e~eral form of these fishes, and external orifices of the branchiz a~e similar to those of the Lampreys, but their fleshy lip is semicircular, and only covers the top of the mouth, consequently they cannot attach themsel~es to bod~es like a true Lamprey. They have no teeth, but the ~p~nmg of their mouth is furnished with a row of small b.ranched c1rr1. They have no particular trachea, and their bran.c h1re are supplied with water from the resophagus as usua1. .T he1r dorsals ar. e united with each other and with the caud a1, 111 orm-mg a low and smuous fold. They inhabit the ooze of brook d h · h b' . s, an t e1r a 1ts are greatly hke those of Worms, which they otherwise so strongly resemble.(!) One of them is found in France, the Petrom. branchialia L . Lam~rillion, Civelle, .&c. From six to eight inches long,' an~ the s1z~ of a large quill; it has been accused of sucking the branch1re of fi_shes, possibly from having confounded it with the Petrom. planeri. It is used as bait. (1) See Omalius de Ilallois, Journ. de Phys., May 1808. d N.B. T~e Petrom: rouge, Lacep., II, i, 2, belongs to this genus, and perhaps. oes not differ mater1ally from the common species quoted. \ |