Ciiiciiiiiafiaii and Lc.viiigfoii Fossils 59 



Maysville, Kentucky, and also in the overlying Corryville. Speci- 

 mens having the same general aspect occur also in the Waynes- 

 ville bed, but usually the latter (plate III, figs. 3, 4) have narrower 

 and more numerous lateral plications. 



Several specimens of Plafystrophia, plate III, figs. 2 A, B, 

 received from Prof. Ray S. Bassler, and labelled as coming from 

 the \\'aynesville bed at Waynesville, Ohio, can not be distinguished 

 from many of the specimens of Plafystrophia laficosta from the 

 upper Fairmount, Bellevue, and lower Corryville horizons at Cin- 

 cinnati, Ohio. 



The later forms of Platystrophia laticosta are distinguished by 

 the comparative distinctness of the lateral plications of the fold and 

 sinus, which, although less conspicuous than the primary plications, 

 are more distinct than in Plafystrophia cyplia. 



It has been suggested that Plafystrophia acitfilirafa was derived 

 fmm Plafystrophia laticosta, but some forms of Plafysfrophicn 

 c\pha also appear available as a source of Platystrophia acitfilirafa. 



Platystrophia crassa, James. 



(Plate IV, figs. 5 A. B.) 



In the Cincinnati Quarterly Journal of Science, vol. i, p. 20, 

 in 1874, U. P. James proposed the specific name crassa for the 

 species illustrated in the OJiio Geological Survey, Paleontology, 

 part 2, vol. I. p. 117, plate 10, fig. 3, under the name Platystrophia 

 denfafa. 



The first specimen figured, illustrated by figs. 3 a-c, has a 

 hinge-line slightly longer than the width of the shell across th.e 

 middle. Onlv two plications occur on the fold, and one in the 

 sinus. The fold is prominent and narrow, and the sinus is cor- 

 respondingly deep. The second specimen illustrated, fig. 3 d, has 

 a somewhat different expression owing to the fact that the hinge- 

 line is distinctly shorter than the width of the shell across the mid- 

 dle. The fold and sinus are similar to those of the first figured 

 specimen, but a small additional plication occurs both in die sinus 

 and on the fold. Neither of the specimens exceeds three-quarters 

 of an inch in width. ]\Ieek, however, included also specimens an 

 inch in width, and he gave the iKM'izon as 250 to 300 feet above 

 low water mark at Cincinnati, Ohi(X This is the horizon from 

 which Meek lis^s also Stroph nnena planoconz'c.va, Dahnanella 



