INVERTEBRATE PALEONTOLOGY. 585 



Named in honor of Capt. William F. Raynolds, ol the United States 

 Topographical Engineers, who brought in the first specimens of this species 

 we had for study. 



Locality and position. — Clear Fork of Powder River, Montana; from 

 the Foil Union group of the Lignite series. We also have it from the Lower 

 Fork of the same stream, from doubtless the same horizon. 



Genus CAMPELOMA, Rafinesque. 



Synon.—Campeloma, Raf. (1819), Jour. Pbys., 422.— Gill (1864), Proceed. Acad. Nat. Sci. Philad., XVI, 

 422 (as a geuus). — Meek (1865), Palsont. Upper Missouri, 114 aud 115; and (1871) 

 Proceed. Acad. Nat. Sci. Philad., XXIII (as a genus) ; also (1872) in Hayden's Second 

 Annual Report United States Geological Survey of the Territories, 299. 



Paludina and Viripara or Fivipanis (sp.), of most authors; but not Paludina, Lamarck, or Vivi- 

 parus, Montfort, as restricted. 



Melantho, of several authors; but not of Bowdich. 



Etym. — wu-ij. a bending; T^Cifia, a margin. 

 Examp. — Paludina pondirosa, Say. 



Shell ovate or subovate, thick and solid ; spire more or less produced, 

 and often eroded at the apex ; volutions rounded or convex ; aperture ovate ; 

 peristome simple, continuous ; inner lip often thick above; outer lip broadly 

 retreating in outline along and above the middle, prominent farther down, 

 and again slightly sinuous around the base of the aperture; axis not distinctly 

 perforated; surface smooth, or only showing lines of growth, with sometimes 

 minute revolving striae, and covered by an olivaceous epidermis. 



This genus was long confounded with Viwparus under the name Palu- 

 dina. As stated in connection with the description of that genus, however, 

 it is readily distinguishable by its more solid, thick shell, thickened inner lip, 

 and the waved or sigmoid outline of its outer lip, as well as by marked differ- 

 ences in the form of its lingual teeth. Like that genus, it inhabits fresh 

 water only, being found in the streams of this country from the Rio Grande 

 to Nova Scotia, and perhaps farther northward. It seems to be strictly an 

 American type ; and we have reason for believing that in the Rocky Mount- 

 ain region, it ranges back to the latest Cretaceous deposits. It is also found 

 abundantly represented in the Tertiary rocks of that region; but curiously 

 enough, it seems not to be represented there by living species. 



We are indebted to Professor Gill for having first called attention to the 



fact that Rafinesque had described this genus as long back as 1819 under 



the name Campeloma. Kafinesque's diagnosis is brief, but it seems to me 



impossible, after an attentive reading of his description — bearing in mind 

 74 h 



