Strophomena and Other Fossils 
39 
8848, and form the originals Jof Figs. 14, 15 and 16, accompany- 
ing the original description. These types are illustrated also by 
Figs. 1 A, B, C on Plate II of this Bulletin 
The specific name was given as a compliment to Miss Hallie 
Cotton, who was the first woman to join the Cincinnati Society 
of Natural History. This name was changed to hallana to Latin- 
ize the term, but halliena would be better if the term be intended 
as a compliment to Miss Hallie, and not Miss Hall. 
The shell is rather small, and subtriangular in outline. The 
larger specimens equal 23 mm. in length, 27 mm. in width, and 
about 7 mm. in convexity. They usually do not exceed 30 mm. 
in width, but occasional!}^ attain a width of 35 mm. Postero- 
lateral angles frequently rounded, but usually rectangular, and 
occasionally even moderately acute. 
The brachial valve is slightly flattened posteriorly, the concavity 
immediately anterior to the beak being almost imperceptible. 
Usually this flattened area does not extend farther than 5 to 7 mm. 
from the beak. From this area the shell curves rapidly downward 
toward the antero-lateral margins, frequently producing long flat- 
tened slopes in this direction, resulting in a sub-triangular appear- 
ance of the shell. The greatest convexity lies along the median 
part of the valve, about as far back as the middle of the shell. 
While the subtriangular outline predominates largely, some spec- 
imens occur in which the form is more nearly semicircular. In 
these the brachial valve is more evenly convex. 
Pedicel valve moderately but distinctly convex immediately 
anterior to the beak, with a reversal of curvature toward the 
middle. The concavity of the pedicel valve usually is small, 
resulting in a rather plano-convex shell. 
The hinge-area of the pedicel valve has a height of scarcely 
2 mm. at the beak, diminishing gradually toward the extremities. 
Sides of the delthyrium forming an angle of about 100 degrees, 
and the deltidium is convex, but, judging from the specimens at 
hand, does not fill up as much of the delthyrium as in other species, 
the chilidium of the brachial valve being mmre fully developed. 
Muscular area approximately circular, bordered posteriorly by 
the teeth, which project only a short distance beyond the hinge- 
area. From the anterior margin of the dental plates, low curved 
ridges extend forward, becoming obsolete immediately in front 
of the area. A narrow median ridge traverses the muscular 
