154 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY — III. 



"Gill-cover8. — Tbo gill-covers are large, and composed of three pieces ; the anterior 

 piece small in some, as is exemplified in the C. maaolcindoUts, and in others large, as in 

 the C. communis; opening or expansion wide. 



^^Noatrih. — The nostrils are double on each side, and separated by a menibrane ; tie 

 largest aperture near the eyes. 



^'Eijia. — The eyes in general are pretty large, a little oblong, without nictitating 

 membrane : pupil black and roundibh : irides yellowish, someliuies Lrown, as in the 

 C. gihhoxuH. 



''Tath. — No teeth in the jaws, but those of the throat, on each side, are composed of a 

 range of bones, generally bluut and thick at their summits, i)laced in a pectinated 

 form, on an osseous, arcuated base, of which they are a Jomponent part, and sonu'- 

 times terminate in a hooked point, as in the C. maculoaus ; these teeth are enveloped in 

 a thick mass of whitish substance, which covers the throat, and supplies the place of 

 a tongue. 



"Month. — The month is generally lunated; to the palate is attached a membrani'. 



'^Viscera. — The inttstinal canal is very much developed, and it has its origin ne.ir the 

 throat ; the stomach, which is simide, and without plaits and curvatures, being a con- 

 tinuation of this canal, and appears to be confounded with it. The intestines make a 

 number of circumvolutions; in a specimen of the C. macrolcpidotus of 16 iuclies 

 in length, they were 3 feet 5 inches in length. The liver is deliquescent, and soon 

 passes into oil after exi)osure to the atmosphere. The air-bladder is subcylindricul, and 

 divided, in most species, into two parts ; in the C. macrolepidofus, it is separated into four 

 parts. I have remarked in the intestines of these fishes river-shells of the genera 

 Lymna'a, JJulimns, etc., which dwell on aquatic plants audou the rock at the bottmn of 

 the rivers; these shells the Catostomi are enabled to take with their lips, which are 

 protruded forwards by means of their jaws. 



" Ifc is necessary to remark that in all the spoaics which I have examined there is a 

 line which runs from the nape, beneath the eyes, and another along the head, above 

 the eyes, of small orilices, for the passage of mucus, which lines are well delined 

 after the fish is dead and desiccated, but not so conspicuous when recent ; these lines 

 Forster improperly terms sutures. I will add that some species, in a dried state, have 

 also a tuberculated appearanco on the head, which tubercles are not discernible wlien 

 the animals are living."— (Lk Sueur, Jonrn. Ac. Sat. Sc i, p. s.).) 



IIvPKNTKi.ifM Ralinesqne, 1H1«.— " This species lExotjlnnhum viarropltrum'] distin- 

 guished by so many secondary characters may be the type of a subgenus, which may 

 be called IJi/pentelium, in reference to the five lobes of the lower jaw. The species 

 with a three-lobed jaw may form then another section under the fi>rmor name of 

 J/rtjri//i»<7Ha."— (RaI'INKSQUK, Joiirn. Jcad. Xat. Se. p. 420, 1818.) 



Catosto.ml's Rafinesque, 18.20. — *' Body oblong cylindrical, scaly. Vent posterior or 

 nearer to the tail. Head and opercules scaleless and smooth. Mouth beneath the 

 snout, with fleshy, thick or lobed sucking lips. Jaws toothless and retractible. 

 Throat with pectinated t*eth. Nostrils double. Gill-cover double or triple. Three 

 branchial rays to the gill membrane. A single dorsal tin commonly opposite to tho 

 abdominal tins, which have from eight to ten rays." — (R.vi'INESQUK, Teh. Oh. p. 53.) 



Decactylus Ralinesqne, 1820. — " Body nearly cylindrical, abdominal tins with tea 



