76 
A ug. F. Foerste 
Orthis interplicata, sp. nov. 
{Plate III, Fig. 44.) 
This form differs only in the greater number of radiating plica- ■ 
tions, a part of them being intercalated between the primary I 
plications. In the specimen figured there are about 21 primary I 
plications, counting all of those initiating at the beak or along the I 
cardinal margin. In addition to these, about 19 secondary plica- j 
tions are added, those near the median line being added within j 
3 mm. of the beak, and those along the side within 5 mm. of the || 
beak. Traces of the beginnings of several additional plications j 
are found near the anterior edge. The interior of the brachial |! 
valve is closely similar to that of typical Orthis flabellites. The |j 
convexity of the valve is moderate, as in the less convex valves of 
Orthis flabellites. 
Osgood bed: New Marion, Indiana. 
Orthis nettelrothi, sp. nov. 
The shell figured by Henry Nettelroth in Kentucky Fossil Shells 
of the Silurian and Devonian Rocks, on plate xxxiv as Orthis fla- 
bellum, also has intercalated plications, but it is a larger, more 
coarsely plicated shell from a higher horizon. 
Louisville bed: from the upper part of the Louisville bed, at the 
Beargrass quarries, east of Louisville, Kentucky. 
Hebertella (Schizonema) fissistriata, sp. nov. 
{Plate III, Figs. 4^ A, B.) 
Brachial valve moderately convex, with a very shallow median 
depression. Cardinal area of medium height, forming an angle of 
about 5° with the general plane of the shell. Cardinal process 
formed by a thin vertical plate of moderate elevation; in addition 
to this plate two narrow striae occupy the space between the crural 
plates, diverging from the cardinal process at an angle of about 25° 
to 30L These are well developed in two specimens, but whether a 
constant feature of this species can not be determined at present. 
From the space between the crural plates, a broad median elevation 
extends forward to the center of the valve. The posterior ad- 
ductor impressions may be traced, but the anterior impressions 
are very indistinct. 
