114 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY III. 



another than in the preceding genera, and arched inward as in Moxostoma, the inner 

 edge of the lower one8 square, its inner margin rising into a broad cusp in the middle 

 and upper teeth." (American Journ. ScL Arts, xix, p. 203.) 



TERETULUS Cope, 1868. "The essential character of this genus is the division of 

 the natatory bladder into three chambers, while Catostomus and all Cyprinida3, exhibit 

 but two. This feature is accompanied by plicate lips, as Agassiz has indicated, and 

 nine rays to the ventral fin, already pointed out by Rafinesque. The species are the 

 largest scaled of the typical suckers. Le Sneur and Valenciennes have pointed out 

 the generic features in the P. macrolepidotus ; Prof. Baird informs me that it occurs 

 in Pt. florealls Bd., and I find it in Pt. cervinus and Pt. duqucsnii. It no doubt exists 

 also in the Pt. aureolus. Other species described by Baird and Girard from the South- 

 west probably possess it. 



"It is difficult to assign a name to this genus. Rafinesque proposes it upon unten- 

 able characters, and includes with it species of Moxostoma and Catostomus. Agassiz 

 purged it of these elements, but did not express its essential character, apparently rely- 

 ing on the plicate lips. I have taken the older name, leaving for others the final 

 decision." (Journal Acad. Nat. Sci. Phila. 18G8, p. 236.) 



PTYCHOSTOMUS Cope, 1870. " The development of the lips furnish important diag- 

 nostic 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 great de- 

 velopment of dorsal fin. Others of this type are more elongate. 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 lips are papillose instead of plicate. 

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



" Rafiuesque proposed a genus Tcretulus on the characteristic peculiarity of nine ven- 

 tral^radii, belonging to most species of this genus. He however included species of 

 two other genera. On this account, Agassiz, in rearranging the suckers, imposed on 

 it the name standing at the head of this article, regarding the plicate lips as a primary 

 character. I think Rafinesque's name is to be rejected, owing to its ill application ; 

 the more as I find two species in which there are ten ventral radii. I adopt that of 

 Agassiz, though 1 showed, when describing the Pt. cervinus, that the tricellular nata- 

 tory bladder was a more distinctive feature. This becomes the*more obvious now that 

 I have found a species where the lips are tubercular instead of plicate." (Proc. Am. 

 Philos. Soc. Phila. p. 460.) 



MOXOSTOMA Jordan, 1870." Dorsal moderate, of 11 to 20 rays : air bladder in three 

 parts : lips usually plicate : lateral line very distinct : pharyngeal teeth numerous and 

 all small, of the usual type, the bones slender" (in comparison with those of Placopha- 

 rynx).(Man. Vert. E. U. S. p. 292.) 



MOXOSTOMA Cope & Jordan, 1877." Body oblong or elongate, with a short sub- 

 quadrate dorsal fin of 10 to 17 developed rays : air bladder in three parts : lateral line 

 present : fontanelle present : scales large, subequal : pharyngeal bones not especially 

 enlarged, the teeth of the usual type." (JORDAN, Proc. Acad. Nat. Sci. Phila. 1877, p. 

 81.) 



