240 FISHES. 



Polyodon, Lac. — Spatularia, Sh. 



These fishes are recognised at once by the enormous prolongation of 

 their snout, to which its broad borders give the figure of the leaf of a tree. 

 Their general form and the position of their fins remind the observer of 

 a Sturgeon, but their gills are still more open, and the operculum is pro- 

 longed into a membranous point which extends to near the middle of the 

 body. The mouth is well cleft and furnished with numerous small teeth. 

 Their upper jaw is formed by the union of the palatines with the maxil- 

 laries, and the pedicle has two articulations. The spine of the back is 

 furnished with a cord like that of the lamprey; and the spiral valve, 

 common to almost all the Chondropterygians, is found in the intestine, 

 but the pancreas begins to be divided into caeca — they have a natatory 

 bladder. 



But a single species is known, the Polyodon feuille, Lacep. I, 

 xii, 3; Squalus spatula, Mauduit, Journ. de Phys. 1774, pi. 11. 

 From the Mississippi. 



Chuvitera *, Lin. 



The Chimaerse are closely allied to the Sharks in their general form 

 and in the position of their fins, but all their branchiae open externally by 

 a single apparent hole on each side, although if we penetrate more deeply, 

 we find that they are attached by a large part of their edges, and that in 

 fact there are five particular holes terminating in the bottom of the com- 

 mon aperture. A vestige of an operculum, however, is concealed under 

 the skin. The jaws are still more reduced than in the Shark, for the 

 palatine and tympanic bones are also mere vestiges suspended to the sides 

 of the snout, and the vomer is the only representative of the upper jaw. 

 Hard and indivisible plates supply the place of teeth, four on the upper 

 jaw and two on the lower. The snout, supported like that of a Shark, 

 projects forwards, and is pierced with pores arranged in tolerably regular 

 lines; the first dorsal, armed with a strong spine, is placed over the pec- 

 torals; the males are recognised, as among the Squali, by bony appen- 

 dages of the ventrals, which are divided, however, into three branches, 

 and they have, besides, two spinous lamina; situated before the base of 

 these same ventrals; a fleshy appendage between the eyes is terminated 

 by a group of small spines. The intestine of the Chimaerae is short and 

 straight, it is furnished, however, with the spiral valve, as in the Shark. 

 They produce very large coriaceous eggs with flattened and hairy borders. 

 In the 



Chimera, Cuv., 



Or true Chimaera, the snout is simply conical; the second dorsal com- 

 mences immediately behind the first and extends to the tip of the tail, 

 which is drawn out in a long filament, and is furnished beneath with 

 another fin similar to the caudal of a Shark. But one species is known, 

 C. monsirosa, L. ; Bl. 124, and Lacep. I, xix, 1, the female; 



• This name was given to them on account of their fantastic figure, which, when 

 they are carelessly dried, as was the case with the specimens first represented by 

 Clusius, A.ldvovandrus, &c, appears monstrous. 



