\< . l!,\ 



1 1 . 

 **. 



' 

 i I. \ i I 7- nun . luirlil 1 I iiiui : tlii.-kni-sii..,4 mm 



Valves viihelliptical. -lightly ol.li.jue. the end- -.ul.e.jiial. tin- li;ick straight nearly 



tn thf po-tcrior extremity: the latter is generally convex ami alnio-t vertical in the 



upl" iurd-. while in th> lower third t he outline merge- rapidly into the uni- 



formly cuir. -in; aiit.'rior end uniformly curved. Surface much the 



highest in t i rior half, with a part prolonged dor-ally into a short and olitu-ch 



point.-, I proniiiKMicc that I.einU ,lo\vn dose to the hinfje line and projects somewhat 



nd it. 'I'hi- prom i delinitin to thr posterior -id.- of a distinct .-iilcn- 



,mo-t half acro-v t: frmn the central part of the dorsal edge, and 



forward alon^ tlie latter. 



Though having a -ulMi<. and therefore agreeing in a general way with I'n'niiliu, 

 I have cho.M'ii t' _-. tlii- . ith /./ i:IH,-ll,i Lecan-e it >eem- to repr. ..... it 



HUM-. ineiit from -ucli typical -pe_cie> of the L'enu- a- /.. inf/<it>i, 



md /. ntUata. Specitically the pr ..... nt form i- readily .'iioii^h di-tin- 



guislu'd l.y (he concentration of the, dor-al promii -er detinition of t he 



snlcu-. The form which I called /'/-//////m ///<//'/-/, * and which occurs in the upper 

 lied- of the Cincinnati group in Ohio and Indiana, has a similar outline, Imt it i- 

 -ome\\hat -mailer and without the dorsal prominence. Still. I would not lie -ur- 

 i to find that it ha- overlapping valves as in 



t Savannah. Illlnolt. A* 



; ,li|.' llk.'l.V II, .11 t! 



!IMII'TKI.I,\ I'lrich. 



nail rJ mm. or le in length). >hort. rouii-i. it^ly 



ronv.-v. more or le-- inflated in the dor-al region, thi- part I.eing the thicke-t ami 

 appeari -ally (in an end \ i. .oulder-like over and out from 



the -traight hinge line: right valve slightly larger than the left and o\ eriapping it 

 along the ventral margin. No e\e tul-erde nor -ulcii-. l.ut a faint central pit and 

 nally present 



I'lrich. 



, 



