NO. 12 PERMIAN BRACHIOPODS FROM OREGON—COOPER 27 
Suborder PRODUCTOIDEA Maillieux, 1940 
Superfamily PropuctacEa Waagen, 1883 
Family PRODUCTIDAE Gray, 1840 
-PROBOLIONIA Cooper, new genus 
Shells usually of small or medium size, subrectangular ; hinge wide, 
usually equal to width at middle or wider; ears prominent, acute or 
forming a right angle; surface costellate but with visceral disk also 
rugose and usually strongly reticulate; spines few in number, gener- 
ally 6 large spines: I on each ear, 1 on each flank just above the ear, 
and 1 on the trail near the sulcus midway between the point of 
geniculation and the front margin. Additional spines present as shown 
by scattered bases but not forming a definable pattern. 
Pedicle valve with reticulated visceral disk, strong sulcus and well- 
rounded flanks; interior with crenulated ridge bounding inner side 
of ear; adductor scars elevated on an elongated platform. Diductor 
scars broad and flabellate. 
Brachial valve concave with strongly reticulate visceral disk, and 
with median fold corresponding to sulcus of pedicle valve; cardinal 
process small, bilobed on ventral face, sessile, trilobed on posterior 
face and surrounded on the dorsal side by a low collar; lateral ridge 
strong; brachial ridges narrow and strongly thickened; visceral disk 
anterior extended anteroventrally to form a strong shelf or diaphragm 
from ear to ear; diaphragm forming interior edge of successive 
trails, several of which may be preserved. Breviseptum short and 
slender. 
Type species—Probolionia posteroreticulata Cooper, new species. 
Discussion—This genus is characterized by its elongate form, 
strong costellae and strongly reticulate visceral disk, paucispinose 
exterior, and the extreme development of the marginal rim or dia- 
phragm. The development of the rim and the successive trails con- 
nected with it are much like the same features in the Mississippian 
genus Diaphragmus (text fig. 2D). 
The one described genus having greatest similarity to Probolionia 
is Kozlowskia. In this genus the spines of the exterior are arranged 
like those of the Oregon shell but Kozlowskia is not deeply sulcate 
and the costellae are never clearly in relief nor as conspicuous as 
they are in the Oregon shell. Furthermore, Kozlowskia is not so 
strongly geniculated and does not have a strongly reticulated visceral 
disk. The interiors of both valves of Kozglowskia are similar to the 
interior of Probolionia but a strong difference in the marginal shelf 
