BRACHIOPODA. 
177 
SlPHONOTRETA (?) MlNNESOTENSIS, Sp. nOV. 
PLATE IV, FIGS. 37, 38. 
Shell subovate in outline. Pedicle-valve more convex than the brachial, slightly 
flattened along the median line, sloping with equal convexity toward the 
lateral and anterior margins. Foramen apical (?). Brachial valve depressed- 
convex, somewhat elevated about the umbo. Surface covered, in the um- 
bonal region, with fine, anastomosing and gently undulating concentric lines, 
which, in the later portions of the shell, are finely granulose or serrated; at 
about one-third the length of the shell coarser varices of growth appear, 
between which the finer lines are retained. Surface covered with hollow 
spines of various sizes, which appear to have been most closely set over the 
umbonal region of the pedicle-valve. Here, where the growth-lines are 
absent, the spine-bases in the original specimen are large and all of about 
the same size and are disposed without order. Over the other portions of 
the shell the spines are set along the edges of the varices, small and large 
being indifferently mixed. The bases of the spines make annular swellings 
on the interior of the valves. The length of the original specimen is 15 
mm., width, 12 mm. 
Trenton limestone. Minneapolis , Minnesota. 
Orbiculoidea (Schizotreta) ovalis, sp. nov. 
PLATE IV E, FIGS, i, 5. 
Shell subelliptical in outline. Yalves with apices situated a little behind the 
center. Lower valve with the apex erect or inclined slightly forward. Ex¬ 
ternal foraminal groove narrow, extending for about one-half the posterior 
radius of the valve. Surface about the foramen convex, but elsewhere slightly 
depressed in its slope from apex to margin. Upper valve more elevated than 
the lower, apex inclined backward, posterior slope gently concave. Surface 
marked by elevated nearly equidistant concentric striae. Shell-substance 
thick, the inner laminae showing fine radiating lines over the anterior region. 
Length of the original specimen, 8 mm., width, 6 mm., thickness through 
the apices of the conjoined valves, 3 mm. 
Trenton limestone. Middleville, N. Y. 
