NO. 12 PERMIAN BRACHIOPODS FROM OREGON—COOPER 29 
PROBOLIONIA ELONGATA Cooper, new species 
Plate 8B, figures 6-12 
Shell fairly large for the genus, longer than wide with a short body 
and long trail. Width of hinge about equal to half the length of an 
adult ; lateral margins slightly rounded ; front margin broadly rounded 
to nearly straight. Body marked by fine, rounded costellae and con- 
centric undulations that are cancellated by the costellae on the visceral 
disk ; trail marked by longitudinal costellae. Entire surface covered 
by fine concentric growth lines. 
Pedicle valve having visceral region about 10 mm. long where the 
valve geniculates at about 90°. Geniculated part of trail continued 
for a distance nearly twice that of the length of the visceral part and 
strongly convex in lateral profile. Sulcus originating at about 5 mm. 
from the beak and extending to the front margin, deepest on the 
geniculated portion of the valve and becoming somewhat shallower 
anteriorly; in section or profile the sulcus makes a broad U with 
narrowly rounded rather than sharp trough. Beak and umbo some- 
what elongated, moderately convex; visceral region moderately in- 
flated and with steep lateral slopes. Cardinal extremities auriculate; 
ears forming a right angle in the adult, acute in the young. Areas 
bounding sulcus on body and trail rounded and with steep lateral 
slopes. 
Brachial valve short and moderately concave, with a concave um- 
bonal region and moderately concave flanks bounding a short, low 
fold that originates at about the middle of the visceral area. Cardinal 
extremities flattened. Visceral region strongly and coarsely reticu- 
lated. Flange well-developed. 
Interior of brachial valve with long and prominent flange around 
the margin of the visceral disk and with the trail given off from the 
flange at an acute angle. Inner flange or margin about 2 mm. in length. 
Measurements in mm.—Holotype, total surface length of pedicle 
valve 37.2, length 21.2, length of visceral region 9.2, length from 
geniculated part to front margin measured on surface 28, hinge width 
20, width 20, height 13; paratype, U.S.N.M. 125372, total surface 
length 41, length 23.0, length of visceral region 10, length from genicu- 
lation to front margin 31, hinge width 20.6, width 10, height 17. 
Types.—Holotype, U.S.N.M. 1253714; figured paratype, U.S.N.M. 
125372; unfigured paratype, U.S.N.M. 125371b. 
Localities —S46, S49, S68; U.O. 2202-3, 2204-3. 
Discussion.—This species is the largest of the marginiferids found 
in the Oregon Permian. Besides this feature it has a strongly convex 
