— 12 — 



122. Unio tuberculatus Barn. River, rather common; 



the larger creeks. 



123. Unio gibbosus Barn. Common in the river; rare 



in the Ohio canal, 

 a. f. ARCTIOR Lea. Not common, nacre white or sal- 

 mon colored; also intermediate specimens between 

 the type and this form, which is hardly to be re- 

 garded even as a variety. 



124. Unio cylindricus Say. River, rare. One large 



and well formed specimen has none of the charac- 

 teristic prominences. Another is peculiar in color- 

 ation, having crowded, fine, dark green with few- 

 light green radial lines, showing nothing of the 

 characteristic pointed markings. 



125. Unio triangularis Barn. River, common. 



126. Unio phaseolus Hildr. River, very common. 



Compared with its size, this species has a very 

 thick and heavy shell. 



127. Unio irroratus Lea. River, common; nacre white 



or pink colored. 



128. Unio pressus Lea. River and Ohio canal, scarce. 



The branchial uteri were found to occupy the an- 

 terior halves of the outer branchiae. It shows de- 

 * cided relations with the following species. 



129. Margaritana rugosa Barn. River, common; 



Ohio canal, scarce. 



130. Margaritana complanata Barn. River, scarce, 



small; Ohio canal, common and quite large; Little 

 Stillwater creek. 



131. Margaritana marginata Say. River, common; 



burrowing deep in the soil, with a long, beautifully 

 orange colored foot. 



132. Margaritana deltoidea Lea. River and Ohio 



canal, rather common. 



133. Marqarinana hildrethiana Lea. River, very 



rare. 



134. Margaritana dehiscens Say. River, rather 



scarce. 



135. Anodonta edentula Say. Common in the river; 



