392 OHIO STATE ACADEMY OF SCIENCE. 
Quadrula.cicatricosa (Say, Unio), varicosa Lea. 
Ohio River. 
Quadrula pilaris (Lea, Unio). 
Ohio River at Cincinnati. 
Quadrula ebena (Lea, Unio). 
Ohio River. 
Quadrula pyramidata (Lea, Unio). 
Ohio River and tributaries; large and heavy specimens in 
the Tuscarawas River. 
Quadrula plena (Lea, Unio). 
Ohio River. 
Quadrula obliqua (Lamarck, Unio). 
Ohio River, and some tributaries. 
Quadrula solida (Lea, Unio). 
Ohio River; Scioto River. 
These last four species are closely related to each other, and 
should be revised. 
Quadrula trigona (Lea, Unio). 
Both drainages, not common. 
Quadrula rubiginosa (Lea, Unio). 
Over the state, generally common.—In some specimens from 
various rivers (Ohio, Tuscarawas, Tiffin), where the 
gonad was for the most part a testis (‘‘males’’), a few 
acini were found to be ovarian, containing ova. 
Quadrula coccinea (Conrad, Unio). 
Over the state, variable. In the Tuscarawas River is a form 
higher than the ‘‘typical’’ one, resembling kirtlandiana 
in shape, but with the soft parts quite different, and 
usually with a few undulations in the middle of the 
disks; it may represent a variety. 
Quadrula coccinea paupercula Simpson. 
St. Lawrence drainage; probably in the state. 
Pleurobema clava (Lamarck, Unio). 
Both drainages; e. g. in the Maumee; not in the Cuyahoga 
River, t. Dean. 
Pleurobema bournianum (Lea, Unio). X 
Scioto River; Ohio River at Cincinnati (Byrnes). 
Unio crassidens Lamarck. 
Ohio River, common; Scioto River. 
Unio gibbosus Barnes. 
Over the state, common and variable in regard to size, shape 
and color of the nacre: dark purple to salmon to white 
(the latter = arctior Lea); a very small form, with the 
beaks more anterior, is in Lake Erie. 
Unio tetralasmus camptodon Say. 
Ohio River at Cincinnati; Great and Little Miami Rivers. 
