212 



U. S. P. R. E. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



An olivaceous tint pervades throughout, rather brownish above and whitish beneath. 



References to the figures. Plate XLI, fig. 1, represents, size of life, a specimen of Pimelodus 

 olivaceus, caught in the Yellowstone river. Fig. 2 is a view from above. Fig. 3, the head 

 seen from beneath. 



Plate XLII represents the same species, size of life, from Fort Pierre, Nebraska. The mouth 

 as delineated in fig. 3 is a good deal too small, by a mistake of the draughtsman. The anal and 

 adipose fins in fig. 1 are likewise somewhat incorrectly drawn. 



List of specimens. 



Family CYPRINIDAE, 



With a few exceptions 1 the mouth is but little cleft, and the jaws weak and toothless, the upper 

 one being formed exclusively by the premaxillaries, behind which the maxillaries are situated. 

 The inferior pharyngeal bones are armed with quite large teeth, the upper pharyngeals 

 being wanting. The base of the cranium, which corresponds to the inferior pharyngeals, ex 

 hibits a process of the skull, in most cases covered with a horny plate. The body is generally 

 elongated, covered with scales, cycloid in structure 2 . One dorsal fin, occasionally provided at 

 its anterior margin with a stout and strong spiny ray, but there is no adipose. The stomach 

 has no cul-de-sac (rceca), and pyloric appendages are also wanting. The swimming or air 

 bladder is in most cases divided into an anterior and a posterior portion, and is furthermore 

 connected with the organ of hearing through a chain of so-called auditive bones. The external 

 surface of the swimming or air bladder is remarkable for the tail-like distribution of its blood 

 vessels. There are four complete branchial arches, the accessory gills (pseudo-branchiae) vary 

 ing according to the genera ; sometimes they are gill-like, comb-like, or even glandulous, in 

 which latter case they are covered by the mucous membrane of the branchial apertures ; at 

 others they appear to be entirely missing. 



STN. C-jprins, Cuv. Regn. Anim. II, 1817, 190. 



Cyprinoides, Cuv. Regn. Anim., 2d ed. II, 1829 ; and, ed. Illustr. Poiss. 214. Cuv. & VAL. Hist. nat. Poiss. 



XVI, 1842, 1. 

 Cyprinidae, BONAP. Sagg. distr. anim. vertebr. 1831, 113. DB KAY, New Y. Fauna, IV, 1842, 188. STOKER, 



Synops. 1846, 154. 



Cyprinoideae, RICHARDS. Faun. Bor. Amer. Ill, 1836, 109. 

 Cyprinoidei (Agass.), MULL, in Weigm Archiv. fur Naturgesch. I, 1843, 319. 



We had contemplated giving more copious details respecting the species of this family than 



Ptychocheilus and Clinostomus. 2 Except Jlulopyge and Mtda, which are scaleless. 



