STROBILOPSID^. O 



Two other series of species appeared first in the Oligocene, 

 one, Eostrohilops, in which the surface is finely striate, begin- 

 ning with S. diptyx, continuing to the Pliocene, S. duvali. 

 The other series, Discostrohilops, contains S. uniplicata (pi. 8, 

 figs. 10-13), which lived from the upper Oligocene to upper 

 Miocene in various varietal forms, and is interesting for its 

 great similarity to the living American S. huhhardi. 



In Europe at its first appearance as now known, the com- 

 plex structure of the genus was apparently about as fully 

 evolved as in any modern species. In the Oligocene, the sub- 

 divisions Strohilops proper, Eostrohilops and Discostrohilops 

 appeared in central Europe, typically developed, probably by 

 migration from somewhere eastward. 



Strohilops doubtless had a long Tertiary history in North 

 America, still to be recovered. At present it is not knoAvn 

 here below the Pleistocene. ^S'. lahyrinthica has been identified 

 from several Pleistocene deposits, the earliest an Iowa deposit 

 believed to be of Aftonian age. S. affinis and S. Idbyrinthica 

 occur from the Sangemon on to the Recent, according to 

 records assembled by F. C. Baker. All of the Pleistocene 

 localities are v/ithin the areas still inhabited by these species. 

 In Bermuda S. huhhardi occurs in Pleistocene lime rock (con- 

 solidated dune formation) and later cave deposits, up to 

 Recent. 



The list of Tertiary species follows. For their classifica- 

 tion see p. 16. 



Strobilops boettgeri (Andreae). Strohilus hoettgeri An- 

 DRE.VE, Mitt. a. d. Roemer Museum, Hildesheim, No. 18, pp. 5, 

 10, 26, text-fig. 5. — Strobilops hoettgeri Wenz, N. Jahrb. f. 

 Min., Geol. u. Pal., 1915, II, p. 80, pi. 4, f. 4a-c; text-fig. 8. 

 Upper Miocene, Tortonian : Oppeln, Silesia. 



Strobilops costata (Clessin). Strohilus costatus Clessin, 

 Corresp.-bl. Zool. Min. Ver. Regensburg, 1877, p. 'il.— Stro- 

 hilops costata Wenz, N. Jahrb. Min., Geol. u. Pal. 1915, p. 79, 

 pi. 4, f. 15a-c; text-fig. 7. — Strohilus hilamellatiLS Clessin, 

 Malak. Blatter, n. F. VII, 1885, p. 79, pi. 7, f. 10.— Strohilus 

 curdoofensis Clessin, Bericht Naturwiss. Ver. Regensburg, 

 XIII (1912), p. 104 = Strohilus xmdorfensis Clessin, t. c, 



