Cornutheca hippocrepis (Leidy, 1874)
Diagnosis: Shell compressed pyriform, with a thick, blunt, solid carina (keel) extending around the shell at the fundus and lateral borders, and ending in long digitate processes projecting downward into the interior of the cavity. Mouth transversely oval, convex downward. Shell transparent, colorless, composed of circular disks; the carina pale straw-colored, homogeneous, indistinctly granular. Test, in color, structure, and arrangement, as in N. collaris and P. carinata. (original description)
Dimensions: Length 252-260 µm; breadth 140-160 µm.
Ecology: Sphagnum swamps, New Jersey.