8 



in the genera Luciocephalus of Blecker,* Percopsis of Agassiz/f and some 

 CharacinsJ where all or some of them are ctenoid. The fins are mostly 

 sustained by branched rays, only the first rays being sometimes simple. 

 The ventral fins are always abdominal. The lower pharyngeal bones are 

 separated, and almost always small and triangular, with the teeth on a 

 plane surface. The air-bladder communicates by a duct with the mouth 

 or intestinal canal. 



This suborder is almost co-equal in extent with the Physostomi of Miil- 

 ler, the Cyprinoids being alone withdrawn. It embraces on our own 

 coasts, the Salmonoids, Olupeoids and similar fishes. 



Suborder EVENTOGNATHI Gill. 



The body, with only three exceptions, is provided with cycloid scales.? 

 All the rays of the fins, except the first of each, are branched. The ven- 

 trals are always abdominal. The lower pharyngeal bones are of a more 

 or less falciform shape, greatly developed, nearly parallel with the 

 branchial arches, and provided on the internal surface of the curved por- 



* " Natuurkundig Tijdschrift voor Nederlandsch Indie," vol. i. p. 273, vol. 

 iii. p. 99. 



f " Lake Superior ; its physical character, vegetation and animals," &c, 

 by Louis Agassiz, Boston, 1850, p. 284. * 



Prof. Baird ("Iconographic Encyclopedia of Science, Literature and Art," 

 translated from the German of Heck, N. Y., 1851, vol. ii. p. 212) has indicated 

 the affinity of Percopsis with the Characins. 



J In a species preserved in the Museum of the Smithsonian Institution, 

 nearly allied to the Xiphostomas of Spix, and especially to the Xiphostoma 

 hujeta of Valenciennes, the scales are covered with numerous closely approxi- 

 mated ridges abruptly commencing at the bases of their exposed surfaces, and 

 terminating in as many strong teeth on the posterior margin. Valenciennes 

 has not described the structure of the scales in the species of Xiphostoma 

 known to him. But he as well as Muller and Troschel in the "Horae Ich- 

 thyologies," have mentioned them as being of moderate size. The ridges 

 and pectinated margins of those of our fish are so strongly marked that it is 

 scarcely possible that they should have been overlooked, if they occurred in 

 the species known to the very excellent naturalists above mentioned. 



The dorsal fin of our fish is more posterior than in the typical Xiphostomas, 

 being above the anal ; the anus is under the anterior rays of the dorsal. In 

 this respect it resembles Xiphostoma maculatum and X hujeta of Valencien- 

 nes. 



Three specimens of the species were collected at Truando, by Mr. Arthur 

 Schott on Lieut. Michler's Expedition to the Atrato river. They will be de- 

 scribed under the generic name of Ctenolucius. It must remain undecided 

 whether the two species of Xiphostoma of Valenciennes, agreeing in the posi- 

 tion of the dorsal and anal fins, are really congeneric. 



The scales of the common " mossbonker" or "menhaden" (Brevoortia 

 menhaden Gill,) and other allied species have also the margins of the scales 

 more or less pectinated. Most of the scales of the Cyprinodont genus Lucio- 

 cephalus of Bleeker or Diplopterus of Gray are also ctenoid. 



The body is destitute of scales in the American genus Meda of Girard, and 

 the very characteristic European Aidopijge of Heckel. But one species of each 

 is known. The typical species of Phoxinellus are also scaleless. 



