Cope.] ^"^ [June 7, 



tremities. The pharyngeal plate has narrow horns directed npwai'ds and 

 forwards, and is thickened medially. It is placed immediately in advance 

 of the opening -of the oesophagus. I have but one specimen of this curious 

 species, which I obtained at Lafayette, on the Wabash River, in Indiana. 



C.VTOSTOMUS, Lesueur. 



60. Catostomus teres, Mitchill. 



Cyprimis teres, Mitch. Gatostomus teres, G. communis and G. hostoniensis, 

 Les. 



Common in all the rivers of the State and on both sides of the Allegheny 

 water-shed. 



61. Gatostomus nigricans, Les. 



C. planiceps, Guv. Val. 



Common in the Clinch, Cumberland and French Broad Elvers. 



An especially western species, and abundant, where it occurs. 



■62. MOXOSTOMA, Rafinesque. 

 MoxosTOMA oblongum:, Mitch. 

 Gatostomus tuberciilatus and vittatus, Lesueur. Labeo oblongus, Dekay. 

 In North Carolina, as in Pennsylvania, this species is confined to the 

 sea-board streams. I only found it in the Neuse. 



PTYCHOSTOMUS, Agass. 



Amer. Journ. Sci., Arts XIX. 88. Teretulus, Raf. Cope emend. Jouru. 

 Acad. Nat. Sci,, Phila., 1868, 235. 



The species of this genus are found in the United States, South of New 

 York and East of the Rocky Mountains, including the waters of the great 

 lakes. They are especially numerous in the rivers of North Carolina, 

 which flow into the Atlantic, and constitute one of the peculiarities of 

 that shed of the Allegheny range, as distinguished from the streams of the 

 western slope in Tennessee, where a smaller number of species is found. 

 "Wherever Ptychostomi occur they are abiuidant in individuals. 



The development of the lips furnishes important diagnostic indications 

 in this genus. In those most nearly allied to Moxostoma, the inferior lip 

 resembles that of that genus, in being narrower, and deeply incised, 

 emarginate posteriorly forming a figure V with the apex forwards ; at 

 the same time the superior lip is very thin, and often narrow. Such 

 species are shorter, and tend to a large development of dorsal fiia. Others 

 of this type are more elongate. The more typical forms have a large 

 inferior lip, which is generaPy produced posteriorly to a square trans- 

 verse margin. Most of these are more elongate species than the last 

 group. Some species of both are distinguished by their very prominent 

 conic muzzle, and minute inferior mouth, reminding one of the Carpiodes. 

 In one species the surface of the lips is pappillose instead of plicate. In 

 some species the mouth is very projectile, in others scarcely so at all. 



