GENUS ICHTHYOBUS. 213 



east of the Allegbanies. No members of the suborders Cycleptince aud 

 Buhaiichthyinw are kuowii from the United States west of the basiu of 

 the Kio Graude. 



The typical species was first described under the name of Amhlodon. 

 The genus Amhlodon of liafiuesque, 1819, is based on the same species 

 as his Ictiobus of 1820. The name Amhludon, however, was given in 

 allusion to the pharyngeal teeth of Haploidouotus grunniens, popularly 

 supposed to be the teeth of the Buffalo tish, the presence of which teeth 

 was supposed to distinguish Amhlodon Irom Catosiomus. This error was 

 afterwards discovered by iiatinesque, and the name Amhlodon trans- 

 ferred to the Scisenoid fish. As Amhlodon of Eafiuesque included the 

 present genera Haploidonotus and Ichthyobiis, erroneously confounded, 

 and as on the discovery of this error its author restricted the name to 

 Haploidonotus, I think that we are justified in retaining Ichthyohus 

 instead of Amhlodon for the genus of Catostomoids. 



Generic Characterizations. 



Amblodon Rafiuesque, 181'.).—" 16. Amci-odon. (Abdominal.) Different du genre 

 Catostomus. Macboire inf^rieure pavee de dents osseuses serr^es arrondies, a couronne 

 plate, in<Sgales. — Les poissons de ce genre, qui abondent daus I'Obio, le Missouri et le 

 Mississippi, sont distiugu^es par Te nom vulgaire de Buffaloe-Fisb (Poisson bouffle) 

 et les Francois de la Louisiane les nomment Picoueau. II y en a plusieurs especes qui 

 parviennent souvent h une tr^s grosse taille. Les deux suivants habitent dans FOhio. 

 1. A. inbalus. Brun olivdtre pdle dessous, joues blanchfitres. D. 28, A. 12, P. 16, A. 9, 

 C. 24. UA. viger est entierement noir; tons deux ont la ligne lat^rale droite, queue 

 bilobde, tdte tronqu^e, etc. lis sont trfes-bons k manger." — (Rafinesque, Journal de 

 Physique, etc. p. 421.) 



Ictiobus Rafiuesque, 1820. — " Body nearly cylindrical. Dorsal tin elongated, abdom- 

 inal fins with nine rays, tail bilobed, commonly equal." — (Rafinesque, Ichthijologia 

 Ohiensis, p. 55. ) 



ICHTiiYOBUS Agassiz, 1855. — " lu the form and position of the fins, as well as in the 

 general outline of the body, this genua is very nearly related to Buhalichthys, but in the 

 structure of the parts of the head, it is quite dissimilar. The mouth opens directly 

 forwards, and is large and round. The lips are small, smooth and thin ; the upper one 

 is not thicker than the interaiaxillary itself, and tapers to <i narrow edge. At the 

 symphysis of the lower jaw, which is larger than in any other genus of this group, the 

 lower lip is hardly more than a thin membrane connecting its smjill lateral lobes. 



"The eye is small, and the opcrcnl .r pieces very large. 



"The scales have many narrow radiating furrows upon the anterior field; none 

 across the lateral fields, few ujwn the margin of the posterior field and these not ex- 

 tending to the centre of radiation. Tubes of the lateral line straight and simple, 

 arising nearly in the middle of ti)e posterior field. 



" Pharyngeal bones are neither flat as in Carpiodea nor triangular as in Buhalichthys, 



