'-"' 



III . V. >/. Sfi. I t'lricll.) 



\\t I Ml. I HiS. M-tl. 



Shell less than medium si/e, the bight varying in thirty-five specimens between 

 7 iniu. and 1"> mm.; width of aperture nearly or quite equal to the bight. Volutions 

 two or two and one-half, rather closely coiled, embracing to a little more than one- 

 half, with a -trong. prominent, flat-topped dorsal keel, from which the surface 

 descends in a wide concave slope; sidas rounding somewhat narrowly into the small 

 open umbilicus; section of volutions broadly cordate. Aperture broad, somewhat 



igular-ovate in outline; outer lip thin, with a moderately deep V-shaped central 

 emargi nation; inner lip thick, vory wide, reflected laterally, extending downward 

 i>\er the preceding volution whose keel shows through very distinctly. Surface 

 with tine straight revolving stri.e, alternating somewhat in strength; transverse or 

 growth lines, excepting an occasional wrinkle, usually very faint, but on the larger 

 specimens they become much stronger and incline to be irregular. Slit-band 

 flat, smooth so far a- known. 



This, the type an. I only known Lower Silurian representative of the praised 

 genu- ftm-'inopsis, reminds one somewhat of the European li. xubxtrintu* Krauss, but 

 the dorsal carina is much more prominent and the slit-band narrower than in that 

 rather doubtful Upper Silurian species. None of the Gotland -penes of the gemi- 



the dorsum carinated. Of Lower Silurian />'.//./,/////</>///-/./, li,-ll, /-.)/'/""' t roost i 

 and />. pl'itystoma are somewhat similar, but as the former has more rounded 

 volutions and the latter quite a differently shaped aperture, there is little likelihood 

 <>f confusion between them even as casts. Being true bellerophons they have of 

 course no revolving lines, while the carina is never so prominent as in Bucanopsis 

 rii. 



We have about fifty specimens of what we take to be the same species from the 



line group at Cincinnati, Ohio. They are, however, smaller than the Trenton 

 form, the hight being in most cases less than 7 mm. and in only one as much as 10 

 mm. Not one of them exhibits even a trace of surface markings although preserv- 

 ing the shell, or rather a replacement of the same in crystalline calcite. But the 

 absence of surface markings on these specimens should not be considered as proof 

 that they were originally without them, since they are wanting also on all the other 

 Gastropoda occurring in association with them. Among these other forms are well 

 known species of Isophospira and ( 'i/rtoliti t he surfaces of which under more 



favorable conditions are always distinctly sculptured. 



Formation and locality.- Upper prt of T; up, near Dmnvlllo, Krnturky: Loral n- uroiip .,f 



th<- Cincinnati period, Cincinnati. Ohl. 



CWtoeion.-E. O. Ulrich. 



