Fossil Mollusks From the John Day Basin in Oregon 



sed; spire scarcely raised above the margin of the last volution; 

 whorls 6, convex-depressed; shoulder of last whorl subangular; 

 umbilicus small; aperture obliquely subquadrate. Locality, Bridge 

 Creek, Oregon."* 



The University of Oregon specimen conforms to the above 

 description almost precisely although it is imperfect. The last 

 whorl at least is missing so that the character of the completed 

 aperture cannot be ascertained and it is believed Conrad's shell 

 was in the same condition. It was thought possible that we actually 

 had here his type, so great is the resemblance, and this may in fact 

 be the case. But if so his drawing fails to show the remnants of 

 a broken whorl about the margin. The shell appears to belong 

 to the Helicidae and it is believed that when a complete specimen 

 is available it will be found to be related to the mormonum group 

 of Epiphragmophora. The genus Zonites in which the species was 

 originally placed is not now recognized as having existed in the 

 United States and the shell certainly does not furnish any evi- 

 dence to show that it belongs to that family. 



Polygyra dalli (Stearns) 



By far the greater part of all land shells thus far collected 

 in the John Day region belong to this species. The University of 

 Oregon Collection contains 90 shells which have been referred here ; 

 among them are many which are well preserved. Many others are 

 fragmentary or young and therefore they have been identified 

 with doubt. 



Polygyrella polygyrella (Bland and Cooper) 



This species lives in the mountains of Idaho at the present 

 time but it was with considerable surprise that a specimen was 

 found in the Oregon Miocene. The shell is not perfect; one whorl 

 at least has been broken away but the characters of Polygyrella are 

 well exhibited. It seems to be somewhat larger than the Recent 

 P. polygyrella with the same number of whorls but there is con- 

 siderable variation in this respect in Recent shells. Perhaps when 

 the aperture shall have been found intact the fossil form will be 

 found to be distinct but without this portion of the shell it is best 

 considered to be the same. 



"Conrad, T. A., Am. Jour. Conch. Vol. 6, 315, p. 13, tig. 9. 1870-71 



[3] 



