3i6 
A ug. F . Foerste 
the pedicel valve is geniculately deflected almost vertically for a 
distance of 6 millimeters. The general surface of this valve is 
gently convex. The concentric Wrinkles characteristic of this 
genus are almost obsolete, the wrinkles being faint but close 
together. About 15 radiating striae occur in a width of 5 milli- 
meters along the anterior margin. The middle one of these striae 
is slightly more prominent. The remainder are very uniform in 
size, and are separated by very narrow spaces. 
Compared with Leptcena gibbosa, James, the shell material of 
each valve is thicker, the striae are more nearly uniform in size, 
there is no concentric depression immediately posterior to the 
geniculate border, and this deflected border is shorter. More- 
over, in Leptcena gibbosa the spaces between the striae appear 
relatively wider, especially along the median parts of the pedicel 
valve. 
Geological position. At the mouth of Emily run, 2 miles west 
of Drennan Springs, in a series of argillaceous limestones inter- 
bedded with greater quantities of clay. The total thickness of this 
clayey section is 18 feet. It is overlaid by coarse limestone, 2 
feet thick, followed by the Southgate division of the Eden forma- 
tion. Below the clayey section containing the Leptcena there 
occurs a series of limestones, 18 feet thick, overlying the typical 
Paris bed with Rhynchotrema incequivalve and Hebertella frank- 
fortensis. The top of the limestone section below the clayey beds 
containing Leptcena is characterized by a rather coarse limestone 
containing a Hebertella with rather more numerous plications 
than is typical of Hebertella frankfortensis. The argillaceous 
limestones and clay section within which the Leptcena was found 
is placed at the base of the Eden formation, but not necessarily 
in the Economy member, whose presence has not been demon- 
strated in the area in question. It may be an extension of the 
Fulton horizon. 
A small specimen of Leptcena, 16 millimeters wide, with a dis- 
tinct geniculate border, and with somewhat finer radiating striae, 
was found in the clayey section overlying the massive argillaceous 
limestones in the railroad cut north of Boyd, Kentucky. The 
exact horizon was ii feet above the massive limestone. It here is 
associated with Trinucleus concentri c us, hut horizon may be 
an extension of the Fulton bed. The heavy limestones at the top 
of the hill section east of the cut probably correspond to the heavy 
