Suborder PHYSOCLYSTI* (Bon.) 



The scales, when present, are either ctenoid or cycloid ; there are rare- 

 ly osseous plates. The anterior rays of the dorsal and anal fins, and the 

 first ray of the ventrals are simple or spinous. The ventrals are generally 

 more or less anterior. The lower pharyngeal bones are small and tri- 

 angular, sometimes united, but generally distinct ; the teeth are implanted 

 on the plane surface. The air-bladder never has a duct communicating 

 with the intestinal canal. 



The group for which we have retained Bonaparte's name of Physoclysti 

 corresponds nearly to the Acanthopterygians, and jugular Malacoptery- 

 gians of Cuvier, and to the Acanthopteri, Pharyngognathi and Anacan- 

 thini of Miiller, the Pleuronectoids being omitted. The differences be- 

 tween those respective groups is so slight, and there is such an obvious 

 similarity between some genera of each that we cannot believe their dis- 

 tinction is founded in nature. We have retained, with Cuvier and Miil- 

 ler, the Pharyngognathan families of Acanthopterygians at the end of the 

 present suborders, but their affinities are probably rather with the Scice- 

 noids, the Chcetodontoids, and even the Percoids. There is indeed a 

 very strong resemblance between the Chromoid genera, Cichlasoma of 

 Swainson or Acara of HeckeU and Geophagus of Heckel and the Percoid 

 Sunfishes (Pomotis of Rafinesquef) and Centrarclii. 



Suborder HETEROSOM ATAJ Bon. 



The chief distinctive feature of this group consists in the unsyminetri- 

 cal body, the eyes being on one side of the head, and the mouth more or 

 less distorted. The side on which the eyes are situated is dark or vari- 

 ously colored, while the eyeless is almost always white. The scales are 

 either ctenoid or cycloid. The dorsal and anal fins are very long, and 

 composed mostly of articulated rays. The ventrals are jugular. There 

 is no air-bladder. 



This suborder was first recognized as an order by Prince Bonaparte. 

 It embraces the well known "Flounders" and "Flat-fishes" of our 

 coasts. 



Suborder PHYSOSTOMI (Miiller.) 



The Scales are generally cycloid, almost the only exceptions occurring 



* Derived from j-Js-a, bladder, and tckeiros, closed, in allusion to the absence 

 of a duct communicating between the air-bladder and mouth, or intestinal 

 canal. 



f Ichthyologia Ohiensis. 



% Heterosomes Dumeril, Zoologie Analytique ou Methode Naturelle de classi- 

 fication des Animaux, Paris, 1806, p. 132, 133. 



Heterosomata Bonaparte, Catalogo Metodico dei Pesci Europei, 1846, p. 6- 

 Dumeril regarded the group as a family. 



