40 AUG. F. FOERSTE 



in the upper half of this rock. Above this are 8 feet of weath- 

 ered clayey limestone in which fossils are very few. This is 

 overlaid by 14^ feet of clay, apparently unfossiliferous at this 

 locality. The name " Mannie shale" is suggested for the shaly 

 clay which forms the upper part of the Richmond in western 

 Tennessee. 



The most common fossil is Rhyfichotrema capax manniensis. 

 A form identified as Dalmanella jugosa is also abundant. A single 

 pedicle valve of Strophomena riigosa [^Strophomena planumbona of 

 the Ohio Survey) was found, exposing the interior, also a single 

 dorsal valve of the form identified as Strophomena planodorsata. 

 Platystrophia cypha is not rare. The largest specimen is 37™°! 

 wide, the postero-lateral angles equal about 65°, the fold of the 

 brachial valve is occupied by four plications, and on each side 

 of the fold there are about twelve lateral plications. In Ohio 

 and Indiana this form extends from the upper part of the Lor- 

 raine to the top of the Richmond. Platystrophia acutilirata may 

 be regarded as the most aberrant variation. One specimen of 

 Platystrophia crassa was found, and one of Plectambo7iites sericeiis. 

 The most interesting specimen, however, is a single specimen 

 of Lingtdasma^ preserving the characteristic ornamentation of 

 the surface, and showing enough of the interior structure to sug- 

 gest its generic relationship, but it is too poorly preserved to 

 warrant a more specific description. It is about half as large as 

 the species hitherto described. 



North of Clifton, both the Richmond limestone and the Rich- 

 mond clay may be traced for a considerable distance along the 

 Tennessee river. Southward, the Richmond thins out rapidly. 

 At the Maddox mill, on Horse creek, a few inches of clayey 

 material intervenes between the top of the Saltillo limestone and 

 the base of the Clinton. In this clay was found a specimen which 

 is identical with Helcionopsis striata in form, but it does not pre- 

 serve the surface striae, being evidently an internal cast. Its 

 length is 2i mm. There is also a single specimen oi Rhyficho- 

 trema capax manniensis, and of Leptae?ia rhomb oidalis . Possibly 



' Pal. New York,Yo\. VIII, Part I, PI. II ; also, Minnesota Geol. Surv., Vol. Ill, 

 Part I, PI. XXX. 



