BRACHIOPODA. 
175 
cular attachments. Crescent distinct, terminal scars very prominent. 
Brachial valve with the umbonal region much thickened; the platform 
sharply V _s haped, its anterior wall being considerably excavated to form 
imperfect vaults; the whole elevation is situated somewhat further forward 
than the opposite valve. A faint longitudinal septum extends a short dis¬ 
tance forward from the apex of the platform. Crown of the crescent faint; 
terminal scars as in the pedicle-valve. 
From the magnesian limestone of the Niagara group, near Cedarburgh, Wis- ^ 
cousin, in association with Dinobolus Conradi, Monomerella prisca and M. Greenii. \ 
Monomerella Ortoni, sp. nov. 
PLATE IV C, FIGS. U, 15. 
Pedicle-valve large, with a high cardinal area, which is gently incurved longi¬ 
tudinally and crossed by lamellose growth-lines, upon which the evidences 
of the deltidial ridges are extremely faint or altogether wanting. Umbonal 
cavities conspicuous, but much shorter than is usual in M. prisca. Cardinal 
slope large, triangular and divided by an axial furrow. Cardinal buttress 
broad at the base but not especially prominent. Platform apparent only at 
its anterior edge where it has a broad anterior slope. Crescent well defined 
beneath the hinge-line; terminal scars very prominent; central, lateral and 
anterior impressions discernible on the platform. Pallial sinuses very strong, 
the outer ramifications from which are distinctly seen. 
Brachial valve unknown. 
From the Niagara dolomitic limestone, at the Rising Sun quarries, Wood 
county, Ohio. 
Monomerella Egani, sp. nov. 
PLATE IV C, FIG. 16. 
Brachial valve with an unusually high cardinal area, indicating a quite ele¬ 
vated beak. This area is strongly striated transversely, and bears two faint 
longitudinal depressions corresponding in position to the deltidial ridges of 
the pedicle-valve. It is continued laterally nearly to the middle of the 
margins. Crescent very narrow over the crown, lying close upon the car¬ 
dinal line; at its turn forward it is developed into a deep, narrow, elongate 
