Fossil Freshwater Mollusks from Oregon 



Type No. 19, 10 paratypes, Condon Museum, University of 

 Oregon. Casts of same, No. 674 Mus. California Acad. Sci. 



Type from University of Oregon locality 212, Warner Lake 

 beds, eastern Oregon. Pliocene. 



This is the largest North American Valvata, one huge broken 

 specimen being almost 10 mm. in diameter. It is characterized by 

 its flat nuclear whorls and generally flat shell. Only rarely is the 

 spire as elevated as the maximum shown in the figures, while great 

 numbers are as flat as the lowest. The thickness of the shells is 

 greater than of any other species seen. Valvata virens from Clear 

 Lake, California, has a uniformly higher spire and is never cari- 

 nated; also the suture is deeper and the peristome is attached to 

 the body whorl in part. In V. oregonensis the peristome is entire. 

 V. utahensis Call " has a uniformly higher spire, deeper suture and 

 narrower umbilicus. Moreover, although it is a carinate species, 

 the nuclear whorls are not discoidal. V. sincera likewise has deeper 

 sutures and an acute apex. The new species of course resembles 

 the various forms of V. tricarinata more than any other but this 

 last does not have all of the variations in the same colony, at least 

 not in the colonies familiar to me. The carinae of tricarinata are 

 high and acute while in V. oregonensis they are rounded when 

 present. Also in tricarinata the sutures are deeper, the sculpture 

 as a rule coarser, and the nuclear whorls are elevated even in the 

 low spired forms of the species. 



This species was briefly described under two names in 1910 by 

 Hannibal. Or at any rate there are two specimens in Stanford 

 University which are marked "types" of V. whitei and V. calli, 

 and they answer to the descriptions which accompany those names. 

 Dr. J. P. Smith kindly permitted casts of them to be made for the 

 California Academy of Sciences where they bear the numbers 643 

 and 644. These species were described from specimens collected 

 near Sumner Lake, Oregon, by F. M. Anderson. Hannibal never 

 published illustrations of his species and later threw both of them 

 into the synonomy of V. tricarinata. 



It may be challenged that all of the variations shown on plates 

 3 and 4 cannot belong to the same species but they all came from 

 a single block of material, the longest dimention of which was not 

 over three inches. Under such a circumstance and with every 

 possible stage of intergradation, a multiplicity of names would seem 

 superfluous. 



V. oregonensis was a very common species in eastern Oregon in 

 Pleistocene time. The University of Oregon collection contains 

 specimens from numerous localities about Warner Lake, Snake 

 River Valley and in Lake County. 



6 Call, R. E. Bull. 11. U. S. Geol. Surv.. p. 44, pi. 6, figs. 1-3. 1884. 



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