FIXED-GILLED OHONDROPTERYGIANS. 253 



CePH ALOFT ERA, DuM*. 



Have the tail slender; the spine, small dorsal, and the pectorals 

 broad, as in Myliobatis ; but the teeth are still more tenuous than 

 those of a Trygon and finely serrated. The anterior part of the head' 

 is truncated, and the pectorals, instead of clasping it, have each of 

 their anterior extremities extended into a salient point, which gives- 

 the fish the appearance of having horns. 



A gigantic species is occasionally captured in the Mediterra- 

 nean, the Raia cephaloptera, Schn.; Raie giorna, Lacep. V,xx, Z,\ 

 with a black back bordered with violet. 



FAMILY II. 



The Chondropterygians of the second family are 

 SUCTORII.— CYCLOSTOMI, Dimer, 



The Suckers, which, as regards the skeleton, are the most imperfect 

 of fishes, and even of all vertebrate animals. They have neither pec* 

 torals nor ventrals ; their elongated body is terminated before by a 

 circular or semicircular fleshy lip, and the cartilaginous ring which 

 siipports it results from the soldering of the palatines to the mandibu- 

 laries. The bodies of all tlie vertebrae are traversed by a single tendi- 

 nous cord filled Avith a mucilaginous substance without strangulations, 

 which reduces them to the condition of cartilaginous rings, scarcely 

 distinct from each other. The annular portion, a little more solid than 

 the rest, is not, however, cartilaginous throughout the whole of its cir- 

 cle. They have no ordinary ribs; but the small branchial ones, which 

 are hardly perceptible in the Squali and Rays, are here greatly deve- 

 loped and united with each other, forming a kind of cage ; while there 

 are no solid branchial arches. The branchiae, instead of being pecti- 

 nated as in all other fishes, resemble purses, resulting from the junction 

 of one face of a branchiae with the opposing one of its neighbour. 

 The labyrinth of the ear is enclosed by the cranium, and the nostrils 

 open externally by a single orifice, in front of which is a blind 

 cavity +. The intestinal cenal is straight and thin, Avith a spiral valve. 



* Cephaloptera, winged head, from the projection of the pectorals. 



t The Raie fabronienne, Lacep., II, v, 1, 2, is most probably a mutilated indivi- 

 dual of the yiorna, but the R. giurna, Lesueur, Ac. Nat. Sc. Philad. appears to differ 

 from tha- of the Mediterranean, and may rather be tlie Mohidar, Duham., second 

 part, Sect. IX, pi. 17. As to the R. hanksienne, Lacep.. II, v, 3. ; — Mcmatia, Id., 

 I, vii, 2. ; — Diabolus marinus, Will., App. IX, .3 ; they unfortunately rest on no 

 authentic foundation. Add the Cephaloptera massena, Riss., p. 15 ; — Erecjoodootenkee, 

 Russ., I, 9. 



X Improperly styled a spiracle. With respect to this family in eeneral, see Dumeril, 

 Diss, sur les Poiss. Cyclostomes. 



