Fossil Freshwater Mollusks from Oregon 



Only one specimen of this interesting species was found at the 

 type locality but it is abundant at locality 207 and shows but little 

 variation. On account of its wide, reamed umbilicus and lack of 

 spiral sculpture or carinse it clearly belongs to the genus Vorticifex. 

 The heavy ribs distinguish it from other species of the genus, even 

 if it were not for its small size. There are costate specimens of 

 Parapholyx packardi in abundance in the same deposit, but in 

 them the altitude of the shell is much greater in proportion to the 

 diameter, the umbilicus is very small or absent, and specimens of 

 the same size only have half as many whorls. It differs from V. 

 tryoni by its smaller size and much coarser sculpture. 



VORTICIFEX, SP. 



Several lots of material from Lake County, southeastern Oregon, 

 contain imperfect remains of a huge costate species of Vorticifex. 

 It is decidedly different from any known species but no specimen 

 is sufficiently well preserved to serve as a type although the char- 

 acters can be fairly well determined from all. The spire is almost 

 flush with the top of the rounded body whorl which is marked with 

 heavy ribs, entirely to the aperture. The distance between these 

 ribs is more than two millimeters and they are as perfectly formed 

 as the sculpturing on any marine mollusk, a unique character 

 among North American fresh-water species. The umbilicus is nar- 

 row, deep and angulated around the margin. The characters of 

 the aperture could not be determined with certainty. This is one 

 of the most interesting discoveries in fresh-water molluscan paleon- 

 tology in the west and it is to be regretted that the species is not 

 represented by well preserved specimens. 



GENUS: LANX CLESSIN 



LANX MORIBUNDUS, N. SP. 

 Plate 1, figures 8 and 9 



Shell ovate, the apex about one-third the distance from the 

 anterior end. Spire elevated and acutely pointed, both inside and 

 outside. Sculpture consists of rough irregular growth ridges, no 

 radial markings; the irregularities of the outside are visible on the 

 inside as concentric ridges of uneven strength. Length, 17.5 mm. ; 

 width, 14.5 mm. ; height, 8.7 mm. 



Type No. 18 University of Oregon. Cast of same, No. 673, 

 Mus. California Acad. Sci. 



Type from University of Oregon locality 210, Warner Lake 

 beds, eastern Oregon. Pleistocene. 



This singular species is the largest of North American fresh- 

 water limpets. The collection at the type locality, where it is 

 fairly common, contains one imperfect specimen which is more 

 than 22 millimeters long; the type is of only average size. The 



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