GENUS ICHTHYOBUS. 213 



east of the Alleghanics. No members of the suborders Cycleptince and 

 Buhaiichthyinw are known from the United States west of the basin of 

 the Kio Grande. 



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

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

 as bis Ictiohus of 1820. The name J.JMZ^Zy^oy<, however, was given in 

 allusion to the pharyngeal teeth of Hoploidoitotus grunnicns, popularly 

 supposed to be the teeth of the Buffalo -fish, the presence of which teeth 

 was supposed to distinguish Amhlodon from Catostomus. This error was 

 afterwards discovered by liafinesque, and the name Amhlodon trans- 

 ferred to the Sciainoid fish. As Amhlodon of Kafinesque included the 

 present genera Haploidonotus and Ichthyohus, 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 Characterizatiovs. 



Amblodon Rafiuesque, 1811'. — " 16. Amblodon. (Abdominal.) Different du genre 

 Catostonnts. Machoire inf6rieure pav6e de dents osseuses serr^es arrondies, a couronne 

 plate, in6gales. — Les poissons de ce genre, qui abondent dans I'Ohio, le Missouri et le 

 Mississippi, sont distingu^es par le nom vulgaire de Buftaloe-Fish (Poisson bonffle) 

 et les Frangois de la Louisiane les uomment Piconeau. II y en a plusieurs especes qui 

 parviennent souvent a une tres grosse taille. Les deux suivauts habitent dans FOhio. 

 1. A. bubalus. Brun olivatre pS-le dessous, joues blancbitres. D. 28, A. 12, P. 16, A. 9, 

 C. 24. L'J. viger est entierenient noir; tons deux ont la ligne lat^rale droite, queue 

 bilobde, tete tionquee, etc. lis sont tr^s-bous a manger." — (Rafinesque, .7oi/r«ai de 

 Physique, etc. ]^. i2l.) 



ICTiOBUS Rafiuesque, 1820. — " Body nearly cylindrical. Dorsal fin elongated, abdom- 

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

 OMensis, p. 55. ) 



ICHTHYOBUS Agassiz, 1855. — " In the form and position of the fins, as well as in the 

 general outline of the body, this genus is very nearly related to Bubalichthys, but in the 

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

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

 is not thicker than the intermaxillary itself, and tapers to a 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 small lateral lobes. 



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



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

 across the lateral fields, few upon 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 the posterior field. 



"Pharyngeal bones are neither flat as in Carpiodes nor triangular as in Bubalichthys, 



