BRACHIOPODA. 
341 
verse section across the umbo of one, shows that the dental lamellae, though 
strong and convergent, did not unite to form a spondylium. Received from 
Professor Safford. 
Trenton horizon (Glade limestone). Near Nashville, Tennessee. 
Orthis (Pl^siomys) loricula, sp. nov. 
PLATE V A, FIGS. 32-34. 
Shell strophomenoid in outline; reversed convex. Hinge-line long and straight 
making the greatest diameter of the shell. Cardinal areas narrow, subequal. 
In the pedicle-valve the delthyrium is covered by a convex plate extending 
for one-half its length; the area is erect, the beak not prominent. The 
valve is slightly convex in the umbonal region but is depressed outward in 
all directions, most strongly in the median line. The brachial valve is de¬ 
pressed about the beak, convex over the pallial region and divided in the 
median line by a shallow sinus. The interior characters of the valves are 
essentially the same as those in Orthis subquadrata. 
External surface covered with numerous fine, elevated striae, alternating 
in size and crossed by finer concentric lines. 
Length of an average specimen, 18 mm.; width, 21 mm. 
Trenton horizon. Fountain, Minnesota. 
Orthis (Dalmanella) arcuaria, sp. nov. 
PLATE VC, FIGS. 20, 21. 
Shell with a general similarity to that of Orthis elegantula, Dalrrfan, but having 
the marginal outline more circular, the pedicle-valve more evenly convex, 
the umbo more prolate, and the brachial valve considerably more convex. 
The pedicle-valve bears a broad fold*, and the brachial a shallow sinus, in the 
median line. In the interior of the pedicle-valve the muscular area is elon¬ 
gate and very deeply impressed, the umbonal portion of this valve being 
considerably thickened. 
