i:;<; THE NAUTILUS. 



Anodonta gracilis Lea. Ohio R., Beaver, 9; Coraopolis, 9. 



Anodonta marginata Say. Ohio R , Coraopolis, 4 : Beaver R., 

 Wampum, 100. 



Margaritana rugosa Bar. Ohio R., Coraopolis, 5; Beaver,!; Bea- 

 yer R. , Wampum, 6. 



Unio aesopus Green. Ohio R., Coraopolis, 3; Beaver R., Wam- 

 pum, 1. 



Unio alatusSsLj. Ohio R., Coraopolis, 14; Beaver, 1. 



Unio coccineus (Hild) Lea. Beaver R., Wampum, 7. 



Unio cooperianus Lea. Ohio R.. Beaver, 1 ; Corapolis, 4. 



Unio contutus Bar. Ohio R., Beaver, 1 ; Corapolis, 1. 



Unio ci/lindricus Say. Ohio R., Corapolis, 1 ; Beaver, 1 ; Beaver, 

 R. , Wampum, 2. 



Unio crassidens Lam. Ohio R.. Coraopolis, 40; Beaver, 3. 



Unio donaciformis Lea. Ohio R., Coraopolis. 2. The larger speci- 

 men is 66 mm. long. 



Unio elegans Lea. Ohio R., Coraopolis, 3. These specimens out- 

 wardly appear like rubioinoms from the same locality, in this respect 

 being much more elongated and less sharply carinated than the typical 

 elegans. 



Unio gibbosus Bar. Ohio R., Coraopolis, 41 ; Beaver, 9; Beaver 

 R., Wampum, 28. 



Unio irrorotus Lea. Ohio R., Beaver, 1. 



Unto kirtlandianus Lea. Beaver R., Wampum, 150. 



Unio lens Lea. Ohio R., Coraopolis, 3; Beaver R., Wampum, 25. 



Unio ligamfintinus Lam. Ohio R. , Coraopolis, 100*; Beaver, 20 ; 

 Beaver R., Wampum, 70. In the Ohio this was the most abundant 

 niollusk, exceeding in numbers all the other Unios put together. 



Unio luteolus Lam. Ohio R., Coraopolis, 16; Beaver R., Wampum, 

 18. 



Unio metaneve.r Raf. Ohio R., Coraopolis, 12; Beaver, 5. 



Unio multiradiatus Lea. Beaver R , Wampum, 14. 



Unio obliquus Lam. (U. subrotundus and varicosus Lea.) Ohio 

 R., Coraopolis, bl ; Beaver, 8. Forty adult specimens of the obliquus 

 type presents so many gradations corresponding on either hand to sub- 

 rotundus and varicosus in the series at the Academy of Natural 

 Sciences named and presented by Isaac Lea, that I am obliged to lump 

 them as above. There is also a complication regarding the appli- 

 cability of the name mytiloides Raf., to some of these. It is probable 



