170 [September, 



CATOSTOMI. 



What distinguishes the Catostomi as a peculiar group, consists, in the first 

 place, in the structure and position of themouth ; it is surrounded with large and 

 fleshy lips, situated under the protruding snout, and has no barbels. The 

 pharyngeal bones are sickle-shaped, varying in the curvature of the dental por- 

 tion and also in the inferior branch. The teeth are numerous, disposed upon 

 one single series ; the inferior ones being longest, the others diminishing in size 

 upwards. To use the expression of Heckel, the teeth are pectiniform {Dentes 

 pectiniformis), that is, arranged like a comb. The anterior margin of the dorsal 

 is situated in advance of the insertion of the ventrals. 



Modifications of these characters, associated with others, will furnish the means 

 of distinguishing the genera. 



The want of more materials upon which the genera Carpiodes, Ictiobus, Buba- 

 lichthys and Ci/cleptus are founded, has prevented us entering into the discus- 

 sion of their generic value. The two following species being the only ones 

 at our command, we introduce them without preamble. 



Carpiodes damalis. Ihave before me a specimen of this species measuring seven 

 inches and three-quarters in total length. The greatest depth of the body is contain- 

 ed about three times and a half in that length, whilst the head constitutes the fifth 

 part of it. The dorsal is much longer than high anteriorly ; its anterior margin 

 is nearer the end of the snout than the insertion of the caudal fin, which is pos- 

 teriorly concave. The origin of the ventrals is situated opposite the fifth de- 

 velojjed ray of the dorsal, the seventh in the series. The pectorals are small. 

 The branchiostegals are three on either side. 



D 27 ; A 10 ; C 4, 1, 8, 8, 1, 3 ; V 10 ; P 16. 



The anterior two rays, in both the dorsal and anal fins, are rudimentary, as 

 also the anterior one in the ventrals. 



The eye is sub-circular ; its diameter being contained four times aud a half 

 in the length of the side of the head. The snout is sub-conical. A line drawn 

 perpendicularly to the angle of the mouth would pass in advance of the pupil. 

 The sub-opercle is largely developed, and contrasts greatly with its reduced size 

 in C. (/.) tumidus. 



The scales are very large ; thirteen lateral rows may be counted from the an- 

 terior margin of the dorsal to the insertion of the ventrals. They are a little 

 higher than long. The lateral line undergoes a slight fall upon the thorax, 

 then runs straightway to the base of the caudal along the eighth row of scales 

 under the anterior margin of the dorsal. 



This species was collected by Dr. Geo. Suckley, U. S. A., in Milk river, an 

 affluent of the Upper Missouri, along the R. R. route explored by Gov. 1. 1. Stevens. 



We have before us half a dozen small specimens from three to three inches 

 and a half in total length, which are closely allied to the preceding species. They 

 were collected in the Arkansas river, near Fort Smith, by Dr. Geo. G. Shuraard. A 

 further identification could not be attempted. 



Ictiobus tumidus. Carpiodes tumidus, B. & G. Proc. Acad. Nat. Sc, Philada., 

 vii. 1854, 28. Should all the sub-divisions of the genus Carpiodes be admitted, 

 then this species, from the Rio Grande del Norte (Rio Bravo), belongs to that 

 of Ictiobus,'^ 



The genus 



MoxosTOMA, Rafin. 



may be circumscribed by characters more natural than the preceding ones. And 

 the most striking of these, it must be conceded, is the absence of that lateral 



* There can be no question about the etymology of this name, from 1x,^!j; and 

 /iovc, which would spell ichthyobus, but Rafinesque choosed to write Ictiobus, 

 which is quite as tasteful, if not more so. The " Nomenclator Zoologicus'' must 

 have satisfied every one, that confusion alone would be the result of re-spelling 

 something like thousands of names. 



