FOSSIL LAND SHELLS OF THK JOHN DAY REGION 655 



mating more nearly perhaps to Jidelis-minor of the Dalles. While 

 Jidelis has its angulated aspect in the hirsute bifumata^ so mormonum 

 exhibits, in the hirsute and carinated hillebraiidi of Newcomb, par- 

 allel aspects of variation. 



Turning from this digression to E. Jidelis^ an examination of forty- 

 seven examples from the forested districts of Coos County, Oregon, 

 which border on the ocean, shows nine that were prominently ele- 

 vated^ Jive conspicuously depressed^ three pathologic in the ordinary 

 sense (had been fractured and mended) and one extremely y?a/, deep- 

 suticred individual, in which each whorl commencing at the apex, 

 was markedly immersed in the succeeding volution, resulting in ex- 

 treme deepening of the suture, a very unusual abnormality and the 

 only example in hundreds of jidelis that have passed under my scrut- 

 iny. These extremes of form, would in fossil shells, destitute of the 

 assistance of color in determining relationship, be regarded as quite 

 distinct, more especially if collected at different times by different per- 

 sons, and at different, though not distant localities ; they testify to the 

 inadequacy of an isolated example, quite likely bleached and weather- 

 worn, as is often the case, as a basis for specific distinction. 



Genus Polygyra Say i8iS. 

 POLYGYRA DALLI Stearns. 

 (Plate XXXV, figs. 4, 5, 6.) 



Helix {Motiodon ') Dallii Stearns (MS.) Bull. 18, U. S. Gaol. Survey, pp. 14- 

 15, pi. Ill, figs. 4, 5, 6, 1885. 



Following Binney's arrangement * the form described below would 

 be placed in the generic group Mesodon^ with the species colum- 

 biana^ devia, townsendiana, etc., of the West Coast, and albolabris, 

 thyroides^ etc., of the eastern side of the continent. 



In this revision I have been governed pretty much by Dr. Pilsbry's 

 recent classification ^ with which, in the main, I agree. 



Shell elevated, subconical, base flattened-convex, imperforate, um- 

 bilical region depressed. Lip moderately thickened and reflected. 

 Surface traversed by fine incremental lines and otherwise marked by 

 minute pits (cicatrices.^), as seen under a magnifier, implying a hir- 



^ Error for Mesodon. 



2 Bull. 28 U. S. National Museum, 1885, and previous publications of said 

 author. 



3 A classified catalogue, with localities, of the Land Shells of America north 

 of Mexico. Philadelphia, April, 1898. 



