1870.] ^'*-^ [Cope. 



traced. This genus will, however, be distinguished from those by the 

 entire want of the lateral external ala common to these and other genera 

 of Cyprinidse. Two species are represented in Capt. King's collection. 



Oligobeltjs arcifeetjs. Cope sp. nov. 



Established on four right and one left pharyngeal bones, none of them 

 with the distal extremity complete. The best iireserved shows teeth 

 2. 3 — , and there is no indication of space for a fourth, though its place 

 of support is lost. 



The proximal line is very strongly curved, and is long and slender. Its 



extremity is neither grooved nor recurved, but slender ; its section would 



be a flat triangle, the inner face about equal to the outer. The size of 



the species equals that of DiasticTius macrodon, the largest specimen 



exceeding any of the latter. It is probably the largest si^ecies obtained 



by Capt. King. 



M. 



Length proximal limb No. 1 0.04 



" " " " 2 025 



Depth near basis first tooth 0065 



Width " " 0085 



Length basis three outer teeth ' Oil 



" two inner " 007 



Nos. 9783, 9791, Catharine's Creek, Idaho. 



Oligobelus laminatus. Cope sp. nov. 

 Established on a left pharyngeal bone which lacks the distal extremity. 

 It differs from the other species of the genus in its broad, flat proximal 

 limb of this bone. Its section is not triangular, but that of a plate with 



a thin outer edge. 



M. 



Width limb just below first tooth 0.008 



Depth " " " " " 004 



The expansion continues to near the proximal end. 



No. 9791. Catharine's Creek, Idaho. 



SEMOTILUS, Rafikesque. 

 I have referred to this existing North American genus two species of 

 the present series, without being entirely certain that such reference will 

 be finally adopted. It is based on the evidence of two pharyngeal bones 

 of two species, one of the right and one of the left side, the foi-mer bear- 

 ing four, the latter five teeth in the larger series. Should the series of 

 the other bone of each prove to have the same number of teeth as the 

 sides preserved, the species will be referable to two genera, the former 

 2.4-4.2 to Ceratichthys, the latter 2i5-5.2 to Gobio, both existing genera. 

 To whichever of the three genera the species are referred, it remains to 

 be one still in existence. 



k5EMOTILUS POSTICUS. CopC Sp. UOV. 



Indicated by a left pharyngeal bone, of which the distal extremity has 

 been broken away. The apices of the teeth of the exterior series are 



