262 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Types.—Holotype: 116821a; figured paratypes: 116821b-i; unfigured para- 
types: 116821j-1. 
Horizon and locality—Pratt Ferry formation (lower 3 feet) in Alabama: 0.2 
mile southeast of Pratt Ferry, Blocton (15’) Quadrangle. 
Discussion.—This species is characterized by its minute size, sulcate brachial 
valve, and upturned pedicle beak. No other species of the genus is known, and 
no other genus has a species quite like it. 
UNDIFERINA Cooper, new genus 
(Latin unda, wave; fero, bear) 
Shell small, subrectangular in outline; hinge straight ; sides and anterior mar- 
gin irregular; anterior margin often emarginate; surface marked by fine, con- 
centric lines of growth; surface often thrown into irregular wrinkles and knobs. 
Beaks small protuberant. 
Brachial interior with median triangular depressed area at the hinge bounded 
by short palintrope with narrow, triangular pseudointerareas ; triangular depres- 
sion occupied by a short triangular plate ; small toothlike projections at anterior 
edge of pseudointerarea; median ridge extending from a point just anterior to 
triangular plate nearly to front margin; median septum highest at anterior end 
with its free edge often modified into a narrow tube; muscle marks not clear, 
but a large muscle seems to have been inserted just under the toothlike projec- 
tions of the palintrope. 
Genotype —Undiferina rugosa Cooper, new species. 
Discussion.—This peculiar little brachiopod presents many unusual features. 
Its exterior and outline are exceptional; the hinge region is not like any other 
inarticulate ; and the median septum is often bizarre in its development. 
The outline and exterior ornamentation suggest a brachiopod that may have 
been attached. The irregular character of the exterior surface with its wrinkles 
and knobs is suggestive of Crania, which often takes the surface ornamentation 
of its host. The irregularity of the margins is similarly suggestive. 
Not in accord with the above views is the straight hinge and the apparent 
toothlike processes on each side of the triangular area. These are suggestive 
of some sort of articular apparatus, but the valve seems to be a brachial valve 
rather than a pedicle valve. The strong median septum and the triangular median 
depression with its thin plate are features of the brachial valve of several genera 
of inarticulate brachiopods described herein. 
Full knowledge of this peculiar shell cannot be had until the pedicle valve is 
known. If this valve should prove to be a cementing one, it may never be found 
with the methods that are at present necessary in collecting this type of material. 
If it is not a cementing form, it should ultimately be found as more etching is 
done. 
This genus in placed tentatively in the Acrotretinae because of the strong de- 
velopment of the median septum, a feature of all known Acrotretinae. 
