SOME NEW SPECIES OF DEVONIAN FOSSILS 557 
Cardinal area probably narrow and small. The cardinal process 
protruding into the pedicle foramen. ‘Teeth large and conspicu- 
ous. ‘The specimen found is an internal mold, but it shows that the 
surface of the shell was covered by numerous radiating striae which 
were crossed by concentric growth lines. 
The interior shows a strongly impressed muscular impression 
on the pedicle valve. This resembles very closely the similar im- 
pression in R. vanuxemi but differs from it in the conspicuous 
divisions characteristic of that species. In the species here 
described this muscular impression extends slightly more than 
half the length of the shell and is divided by a prominent median 
ridge. The brachial valve shows a slight rounded median ridge 
which extends about a third of the length of the shell and is con- 
tinued backward into the cardinal process. The muscular impres- 
sion in this valve is poorly defined. The crural processes are 
prominent as in R. vanuxemi. While this form resembles closely 
R. vanuxemi it is somewhat intermediate between that form and 
R. penelope. 
Horizon and locality.—Amherstburg dolomite, Stony Island Dry 
Cut in Livingston Channel, Detroit River, near Trenton, Michigan. 
Schizophoria prima n.sp. 
PraTE II, Fic. 3 
Shell transversely elliptical or roundly quadrate, moderately 
convex. Hinge line approximately straight and equal to about 
half the width of the shell. 
Brachial valve unknown. Pedicle valve with rather prominent 
umbonal region and sloping abruptly to the cardinal area and 
extremities. In other directions from the umbonal area the valve 
is more or less flattened (possibly accidentally) but abruptly curved 
downward at the margins. The front third shows a broad ill- 
defined sinus which makes but a slight impression on the front 
margin. Surface marked by fine radiating striae, which are poorly 
shown on the internal mold. Concentric growth lines are also 
visible. 
The internal impression of the pedicle valve shows a rather small 
subquadrate muscular scar, which is bordered by a deeply impressed 
