Black Shale of Eastern Kentucky. 391 



Locality and position. In the base of the Devonian black 

 shale, supposed to be of the age of the Genesee shale of New 

 York, near Jefferson ville, Montgomery Co., Kentucky. 



Orbiculoidea sp. 



Associated with the other fossils from the vicinity of Jeffer- 

 sonville is a single dorsal valve of a small Orbiculoidea. It is 

 nearly circular in shape, slightly truncate posteriorly and with 

 the usual ornamentation of concentric lines! The diameter is 

 31mm an j f.j ae e xcentric apex is situated near the truncate end, 

 from which it is about l mm distant. In its size and other char- 

 acters this shell much resembles Orbiculoides minnta. 



Locality and position. At the base of the Devonian black 

 shale, supposed to be of Genesee age, near Jeffersonville, Mont- 

 gomery Co., Kentucky. 



Leiorchynchus quadricostatum Vanuxem. 

 Fig. 5, p. 395. 



Orthis quadricostata Yanuxem, 1842. Geol. New York, 

 Kep. Third District, p. 168, fig. 2. 



Leiorhynchus quadricostata Hall, 1867. Pal. New York, 

 vol. iv, p. 357, pi. 56, figs. M-49. " 



Much the same characters and the same range of variation 

 are shown" in the Kentucky representatives of this shell as in 

 those from the typical localities. The fold and sinus usually 

 contain 3 or 4 coarse plications, but sometimes also a larger 

 number of finer ones. I have counted as high as 7 or 8. The 

 sides are almost smooth, often showing two or three broad 

 indistinct folds, but occasionally numerous finer but yet not 

 strong radiating stria?. 



I have referred this species to L. quadricostatum rather than 

 to L. mesicostale because of the nearly constant obsolescence 

 of the lateral plications. 



Common in the strata from which collections were made. 



Locality and position. At the base of the Devonian black 

 shale, supposed to be of Genesee age, near Jeffersonville, Mont- 

 gomery Co., Kentucky, and near Indian Fields, Clark Co., Ken- 

 tucky. 



Plethospira Ulrich, 1897. 



Plethospira socialis n. sp. 

 Figs. 1, l a ,2, 2 a , 3, 3 b , p. 395. 



Shell small and consisting of about three rapidly expanding 

 volutions. The spire is low and small, the final whorl particu- 

 larly large. Underneath, the shell is concave, and while most 



