SOUTHERN CALIFORNIA ACADEMY OF SCIENCES. rg 



Cope, and by Professor Condon of Oregon, in the "John Day 

 Region," a noted fossil locality, were submitted to Dr. R. E. C. 

 Stearns of the Smithsonian Institution (now a resident of Los 

 Angeles), who recognized specimens 0:fl a supposed ancestral 

 form of the Ammonitella which he named Ammonitella Yatesi 

 prascursor, and with these he found ancestral forms of other 

 membersj of well known and widely distributed living species 

 of the family of Helices, especially the Epiphragmophora fidelis, 

 from which many of our recognized living species originated. 

 This fossil form Dr. Stearns described as E. fidelis antecedens ; 

 Of the Ammonitella (also called Gonostoma Yatesi), Dr. 

 Stearns says : "The Cope-Condon collections contain four spe- 

 cimens (Mus. No. 13,403) of this interesting and curious form. 

 It is apparently the forerunner or ancestor of the living A. 

 Yatesi described by Dr. Cooper from specimens collected by 

 Dr. L. G. Yates in the cave at Cave City, Calaveras County, 

 California, m 1869."* The restricted distribution of A. Yatesi 

 and the smaller size of the recent, compared with the fossil 

 examples, suggest obsolescence, as well as a survival of the ex- 

 traordinary physical changes of the John Day Epoch." 



Dr. Charles A. White in paper "On the Marine Eocene, 

 Fresh Water Miocene, and other Fossil Mollusca of Western 

 North America," says.f "It is so apparent, from the evidence 

 furnished, that these fossil forms represent the living species an- 

 cestrally that one may reasonably make the same use of them, 

 with reference to their genetic history, as if the continuity of 

 that history were known by actual observation. These forms, 

 whose genetic history and specific identity have so evidently 

 been continued in unbi;oken lines from the John Day epoch to 

 the present time, have endured remarkable vicissitudes of 

 physical conditions as well as considerable geographical disper- 

 sion since Miocene time. Some of the changes which have taken 

 place in that region since then are very remarkable. 



"One of the greatest volcanic outflows which the earth has 

 known, covering thousands of square miles with melted rock and 

 forming the great mountains of the Cascada range, occurred in 

 and near that region since those mollusks lived upon the bor- 

 ders of the John Day lake. The Glacial epoch has come and 

 gone since then, and an immense subaerial erosion has taken 

 place over the whole region, the extent of which one cannot 

 comprehend without witnessing its results. Not a mammalian 

 species or genus now exists indigenously upon the North 

 American Continent that existed then, and alF other vertebrate 

 forms of continental life have materially changed ; but living 

 descendants of those land snails are thriving today in the same 

 region and under the same specific forms that their remote an- 

 cestors bore." 



It will be seen by comparison with' the present status of 



