ItM'A 

 l lr 



EOTOMAKIA ELKVATA, H. Sp. (I'lricll.) 

 IE LXX. FItiS. . 



i resembling Loptatpim; width 15 mm.; htght about 90 mm.; bight of aperture about 12 mm. 

 utloD* four or five, the last comprising much the greater part of the bell, slightly. 

 iiirr.-tt.-l. tii.- upper slope nearly flat; band slightly concave, the outer border forming the angular 

 periphery of the whorls, tin- inn.-r tx.nl.-r. -.insisting of a sharply derated thin line; band very wide, occupy- 

 ing nearly two-fifths of the sloping space between the periphery and suture ; base large, lu surface moder- 

 ately convex, with a slightly concave band a short distance beneath the periphery; aperture obliquely sub- 

 quadrate or subtrlangular, narrow below, the bight greater by a fifth or a sixth than the width ; columellar 

 Up thick, reflexed, almost entirely covering the minute umbilicus; surface marked distinctly though 

 rather Irregularly with lines of growth, strongly recurved above, more gently below ; lunula> of band uni- 

 formly curved, unequal, occasionally strong. 



The fact that the band Is placed wholly above Instead of on the periphery of the whorls, dlstln- 

 nui-hethls peculiar shell at once from LopAofpira, several species of which It resembles In form. The 

 great width of the band may suggest relations to Omoipira, but the uniform ruivature of the lunule 

 proves that thy species belongs to the Pleitrotomartidai and not to the It>tphi*tmnidir. In placing the 

 species under JSotomaria we have been guided principally by the position of the band. 



formation and locality. Upper part of the Trenton group, Hartoville, Tennessee. 

 Oollettion. E. O. Ulrlch. 



Genus CLATHROS1MKA. n. gen. 

 I'leurotomaria (part.) of numerous American and European authors. 



For generic characters see page 954. 



In this genus we propose to include subconical or turbinate shells differing from 

 Eotomaria in having a delicate cancellated surface sculpture and the band, which is 

 of the concave type, placed vertically and directly upon the periphery of the whorls 

 The outer lip is merely notched, not slit as in Pleurotomaria and similar genera 

 The group is represented by at least three species, two of them new, in Lower 

 Silurian strata of America, and by four possibly six European species that Lind- 

 str<>m has described from the Upper Silurian rocks of the island of Gotland, under 

 the following names: Pleurotont 'usfrntn. P. ylandiformis, P. hindei, P. latezonatn, 



P. gradata and P. scutulata. The last two of these six species, though agreeing in 

 most respects very well with /'/. sul'i>nii-u Hall, the type of the proposed genus, are 

 peculiar in having a pair of thin elevated lines just above the center of the slit-band. 

 The significance of these lines is not clear at present, but we suspect that they 

 represent homologically the median line of the band of fopho.ipira hirinrla, and if 

 that is a fact, then the species in question cannot belong to Clnlhrospira, for thi< 

 genus and Ijophospira are widely distinct genetically. 



As near as we could learn, all of these Gotland species agree with the American 

 species in having no slit. All diller, however, in having the anteriorly curved 

 portion of the lines of growth just beneath the band much shorter and the anterior 

 outline of the lower lip, as seen in a view of the base, much straighter. But this 



