122 FISHES. 



species abound in both oceans*. Their form is oval or oblong; we may 

 separate from them the 



POMACANTIIUS, CuV., 



In which the form is more elevated; a circumstance resulting from the 

 more sudden rise of the edge of the dorsal-]-. The only species known 

 are from America. 



Platax 



Have in front of their brush-like teeth a row of trenchant ones, each 

 divided into three points; the body, strongly compressed, seems to be con- 

 tinued into thick, vertical, elevated, and scaly fins, in whose anterior edge 

 some few spines are concealed, so that the whole fish is much higher than 

 it is long; very long ventrals. The whole of the subgenus are found in 

 the Indian OceanJ. 



One species, Ch. arthriticus, Bell. Phil. Trans. 1793, pi. vi, of a 

 more orbicular form, is remarkable for the knots or enlargements in 

 some of its interspinals and spinous apophyses §. 



A fossil species of this subdivision has also been discovered at 

 Mount Bolca||. 



Psettus, Commers., 



Have, with the figure somewhat resembling that of a Platax, the teeth 

 small and dense as the pile on velvet, and the ventrals reduced to a single 

 small spine, without soft rays. 



The form of some is elevated^f; that of others round or oval**; they 

 are all from the Indian Ocean. 



PlMELEPTERUS, LdCep., 



Are distinguished from all other fishes by a single range of teeth placed 

 in a horizontal base or heel, on the anterior edge of which is a part verti- 



* American species, Chat, ciliaris, L , Bl. 214, or Isabelita, Parra, VII, 1, or 

 Chat, couronne, Desmar. Dec. Icthyol.; — Chat, tricolor, Bl. 425; Duham. Sect. IV, 

 pi. xxiii, 5. India species, Chat, bicolur, Bl. 206, 1 ; — Ch. mesoleucos, Bl., or meso- 

 melas, Gm., Bl. 216, 2; — Holoc. amir alis, Cuv., Ren. I, xvi, 92; — Ch. annularis, Bl. 

 215, 2; — Ch. imperator, Bl. 194; — Ch. fasciatus, Bl. 195; — Ch. nicobariensis, Bl. Schn. 

 50, or Geometricus, Lacep. IV, xiii, 1; — Hoi. Lamarlc, Lacep. IV, 531, Renard, I, 

 xxvi, 144, 145, and several new species. 



f Chat, atireus, Bl. 193, 1, or Chirivita jaunc, Parra, VI, 2; — Chat, paru, Bl. 197, 

 or Chirivita noir, Parr. VI, 1; — Ch. H-cinclus, Cuv., Guaperva, Marcgr. 178; — Ch. 

 arcualus, L., Bl. 204, 2. 



% Chat, vespertilio, Bl. 199, 2;—Ch. te'ira, lb. I; — Ch. guttulatus, Cuv., Ren. II, 

 xxiv, 129. 



§ It is also the Ch. pentacanthe, Lacep. IV, xi, 2, and the Ch. orbicularis, Forsk., 

 or Acanthinion orbiculaire, Lacep. IV, 500. 



|| Ittiol. Veron. pi. 4 and 6. 



^f Psett. Seba, Cuv., Chatodon rhombeus, Bl. Schn., Seb. Ill, xxvi, 21 j — Ps. 

 rhombeus, Cuv., or Scomber rhombeus, Forsk., or Centrogaster rhombeus, Gm., or Cen- 

 tropude rhomboidal, Lacep., Russ. 59. 



** Psett. Commersonii, Cuv., or Monodactyle falciforme, Lacep., II, v, 4, and III, 

 131, which very probably does not differ from the Chat, argenleus, L., or Acanlho- 

 pode argente, Lacep. 



