Cope.] 468 (June 7, 
tremities. The pharyngeal plate has narrow horns directed upwards 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. 
CATOSTOMUS, Lesueur. 
60. CaTostoMus TERES, Mitchill. 
. Cyprinus teres, Mitch. Catostomus teres, C. communis and O. bostoniensis, 
Les. 
Common in all the rivers of the State and on both sides of the Allegheny 
water-shed. 
61. Carosromus NIGRICANS, Les. 
C. planiceps, Cuv. Val. 
Common in the Clinch, Cumberland and French Broad Rivers. 
An especially western species, and abundant, where it occurs. 
62. MOXOSTOMA, Rafinesque. 
Moxostoma OBLONGUM, Mitch. 
Catostomus tuberculatus and vittatas, 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. Journ. 
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 abundant 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 fin. Others 
of this type are more elongate. The more typical forms have a large 
inferior lip, which is generally 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. 
