OPODA 'I I 7 



i 



next tin' lines of growth are more regular ami -harper, then tin- -lit -lian<l i- mmc 

 truly a l-au-l though on the whole loss prominent, while the lunultu are sharply 

 li'iiiii-.l. Finally, the inner lip is scarcely as broad though its inner margin is 

 heavier, while the prominence of the central boss is emphasized by a deep and large 

 Depression on each -i<le of it We know of no other species with which //. 

 need be compared, excepting two or three of those next de-criU>d. 



and locality. Tr. ;p Krunkr..rt, K.-nturky, and noar Nahllle, TYn 



CMtettm.-E. O. ririch. 



P.KI.I.KI: .ii-iios- HII.INKATI s. n. sp. (Ulric/t.) 



n.ATK i. xiv. noa. -si. 



Very much lik. -//'. only smaller, narrower across the aperture, with fine 



an. I sharper, as well as more regular, lines of growth, and much less prominent 

 slit-1'aml. The latter is concave, lies between two sharp lines and is crossed by 

 rat her li-tinct lnnuhr. The posterior curve of the lines of growth on the dorsum 

 also is broader, while the inner portion of the lower lip is much less thickened. The 

 last difference is even more conspicuous when we compare the species with II. claustw, 

 and this, coupled with the fact that the umbilicus is closed in that species and 

 rather large in li. l>ilinffitiu, renders confusion with that form quite improbable. 



FtrrmalioH and locality. Upper portloa of the Trenton group, near Danville, Kentucky. 

 CMtetfo*. E. O. Ulri.-h. 



HRLLRROPHON SUBOLOBOLUS, n. sp. (Ulrich.) 



I'l.VTh IAIV. I li,<. 17 and !. 



This also reseml'li'- /'. trn,,<t; very closely, but good testiferous examples may be 

 <li>tinKtii-ln"l without much troiiMe. The surface striae, though their direction 

 with respect to the dorsal keel is nearly the same us in li. trooxti (the retral curve 

 on the back is somewhat wi<lfi). are more regular, sharper and thread-like. Com- 

 paring other character- it is found that the volutions are more ventricose and more 

 uniformly rounle<l. can-ing the shell as a whole to be more globular, the keel 

 i- less prominent ami thinner, the aperture is more rounded and less 

 expanded transversely, and the callosity of the inner lip not so great probably 

 much less. (In all of our specimens of this species the mouth is obscured by an 

 incrustation of siliceous material so that we cannot tell exactly about the callosity 

 of the inner lip.) B. ntbglobulus is distinguished from li. rlnumt* l>y similar 

 litterences. while the presence of a small umbilicus adds another, the umliilicu- 

 being closed in that species. In H. liil< iie uml.ilicu- i- larger and the slit 



concave instead of rounded. 



