GASTROPODA. '" 



..plrm-J 



etuis Safford sp.. / (MrlMft lr., /. i>irt'<>ratu I', ami S.. / / <mema U. ami S. 



lnna U. ami x . /. /"//</</>/</<<'/ I'lr.' 



Ifni sulwti.,n: High shell.-, eight to twelve whorls, less angular than 

 in preceding suli ..... turn. Species: L. bowdeni Safford sp., L. producta Ulr., /.. migus- 

 tina Hilling- ~p . '/.. //<;;<>; Mall -p., /.. ni(irr<>xj>ir<i Mall sp. 



8. Cirrliti subsection:- I'itl.-r- from 1 in having a much higher spire, and from 

 J in having more numerous and more sharply angular volutions. Species: L. rirelin 

 Hillings sp.. L. fxtrllii Hillings sp., L, extenuutu Mall sp. 



4. Scrruliita subsection. Distinguished from 1 by the plate-like extension and 

 wavy character of the central part of the peripheral carina. Only known species: 

 L. serrulatn Sal tor sp. 



H. Ricinda section: Lines of growth curving very slightly, or not at all, back- 

 ward to the peripheral keel, the apertural notch being very shallow. 



1. ' subsection: Surface markings fine, generally quite regular, sharply 



elevated and closely arranged. Species: L. bidnctn Mall sp., L. quadrisulcata U. and 

 v L.obliqua ('. and S., L. Inimilis Ulr., L. amdnnula U. ami S., /.. fillm<>rensis U. 

 an ntpera Billings sp. 



Tubulosa subsection: Similar to preceding, but surface markings much 

 stronger, lamellose and imbricating, particularly on the band. Species: L. tubulosa 

 l.i mist rom sp., L. la>jneatti LindstrOm sp., both from the Upper Silurian of Gothland. 



3. Imlirinita subsection: Relatively high small shells, with coarsely lamellar 

 imbricating lines of growth; the latter turn backward on the basal portion of the 

 whorl very soon after leaving the peripheral band, the aperture being unusually 

 oblique. Species: \furchisonia imbricata, munda, tortuosa, cochkata and perhaps 



11 I'ppor Silurian of Gothland and described by Lindstrom. Unknown 

 in America except by an undescnbed species in the Clinton iron ore of New York. 



4. Hitlmi subsection: Lines of growth fine and equal as in the Bicincta sub- 

 section hut with a direction as in the preceding. Only known species: Plmrotemaria 

 hvhni LiniUtniin iiiothland.) 



>-ter?3 subsection: Agrees in all respects with the Bicincta subsection 

 excepting that the last whorl or two is free. Only known species: L. helicteret 

 Salter sp.f 



C. Ifobustn ttetinn:- Shells rather short, whorls romparatively rounded, vontri- 

 coee, scarcely angular even at the peripheral hand, which is .h-tinctly trilineate. 



i w ' . I. .- ..... I . r -,'. 



ih laUod oCOothlMd p>eH at nmntamu ! xUf H , nf t.,. U I. iH-.utifulljr I; 



pl.u- VII I of kto gnat work on Uw -Hllarlan (HMtopod* , 



f n.n, Ur. l.lJtrflm. prore It to be oalte dUilnri from the Amvrlca kMwta 



JWunMnnto MhUd and M. tnpUoflttn of WbllMVW. froto UeOorlph of Cnd. f..r which ihr .uttma /xtmplurw ! 

 propawd by FUclMr(IUaul Ccweb^ p.(47; IMA.) mmy twloocto thl. .UK H la the alMMM* of ralUMr 



' 1 1* elwracun of U peripheral bud awl ap*rurl alnoa. w* prater lo tear* tbra aadMll. 



