LAKE SUPERIOR. 



prolongation of the rostrum. The mouth is small ; the lips which 

 border it are much reduced, smooth, never carunculated, and do 

 not extend themselves on the lower jaw under the form of lobes. 

 This character is well represented on figure 2 of PI. 2. At the 

 angles of the mouth, the upper lips bend slightly forwards to join the 

 middle of the branch of the lower maxillary ; they here form a 

 small tunnel, on whose outer margin is a small barbel, sometimea 

 very difficult to recognize. To this genus we must refer the Lends- 

 cus atronasus (Cyprinus atronasus Mitch.^ and L. nasutus Ayres. 

 Though the first of these species has not the character of a very 

 prominent rostrum, the structure of the mouth, and the presence 

 of the barbel, justify this approximation. 



There are still other species of this genus found in the United 

 States, yet imperfectly known, which will hereafter also take their 

 place here. Anatomical study will doubtless reveal other characters 

 than those which external conformation already gives, and will also 

 teach us the value of this singular group in the family of Cyprinoids. 

 At present I cannot help considering the Rhinichthys of North 

 America as a diminutive of the group of the Labeos of Africa and 

 the East Indies. 



Rhinichthys marmoratus, Agass. 



PI. II., figs. 1 and 2. 



This species is one of the largest of the genus, at least, of those 

 which are as yet known to us. The form is elongated, subcylindrical, 

 compressed. The tail preserves just proportions with the trunk; its 

 two margins are almost straight. The ventral line is a little convex, 

 and rises abruptly at the insertion of the anal. The back is feebly 

 arched from the dorsal fin to the nape of the neck, where the slope 

 continues rapidly from the skull to the snout. The head is entirely 

 smooth ; it is small, conical, and well proportioned to the body, in 

 whose whole length it is contained four times. The upper surface ia 

 rounded ; the eyes are of medium size, and situated near the upper 

 margin of the face, at about an equal distance from the end of the 

 rostrum and the upper angle of the operculum. The nostrils are 



