BRAcHIOPODA. 785 
Kayseria, Davidson. 1892. 
(Plate 36, figs. 1, 2.) 
Shell small, with depressed-convex or lenticular valves, radially 
plicated exterior and a median, plicated sinus on both valves. 
On the interior the pedicle-valve bears a low, thickened median 
ridge, but is otherwise devoid of pronounced peculiarities. In 
the brachial valve there is a high median septum which arises 
from beneath the divided hinge-plate and reaches its greatest 
-elevation at a point behind the center of the valve, whence it 
descends rather abruptly, traversing altogether about two-thirds 
the length of the valve. 
The spiral cones form sharp angles with the crura, and are 
directed laterally; the jugum is very stout, taking its origin at 
about one-third the length of the primary ribbon; it is directed 
somewhat posteriorly, its lateral elements uniting to form a short 
saddle which rests upon, and is supported by the most elevated 
part of the median septum. Posteriorly the jugum is continued 
into an upright simple stem, which is 
continued completely across the um- 
bonal cavity and comes into contact 
with the opposite valve, resting upon 
the median ridge of that valve or 
with its extremity inserted into a Seno IGE ia weauiesen tan 
groove upon that ridge. The acces- Phillips (p.). 
sory lamellz originate from a posterior elevation or process arising 
from the saddle of the jugum and are given off at points just in 
front of the crural angles. The ribbon of the principal spiral 
cones is comparatively broad, thickened on the inner margins, 
making six or seven volutions in a full-grown shell. The acces- 
sory lamella are also produced into spirals which though more 
delicate are composed of as many volutions as the principal spirals. 
_ At their outset the branches of the accessory lamelle pass 
between the first and second volutions of the principal ribbon, 
and the two are intercoiled in this manner for their entire 
extent. 
Type, Kayseria lens, Phillips (sp.). Middle Devonian. 
But a single species is known. 
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