OBSERVATIONS. 



A striking similarity exists between this shell and the 

 mneatus and gibbosiis of Barnes, the latter of which, how- 

 ever, is somewhat more slender, the cardinal teeth larger, 

 the lateral teeth longer, and the beaks undulated. 



In a note on Dr. Hildreth's description of phaseolus, 

 Barnes says it is a " white variety of cuneatus ;" and it 

 must be confessed that a considerable resemblance exists 

 between some of their varieties. But the latter species 

 differs in the much less dilated cardinal plate ; in having 

 the anterior smaller muscular impression, situated imme- 

 diately beneath the tip of the lamelliform teeth ; in hav- 

 ing the anterior lunule much more depressed, with slight- 

 ly elevated lines crossing the wrinkles. 



The young, of a corresponding age, accurately resem- 

 bles, in its outline, Barnes' figure of his mucronatus, but 

 his description of mucronatus agrees better with cuneatus 

 than with any other species, certainly much better than 

 with gibbosus, inasmuch as it is stated to be "purplish on 

 the margin and whitish in the centre," whereas the latter 

 is more commonly whitish on the margin than in the cen- 

 tre, and the "anterior lunule long, distinct, with a marginal 

 furrow," of mucronatus, agrees with cuneatus, but not at 

 all with gibbosus. 



This species is found in plenty in the Wabash, and is 

 probably also an inhabitant of most of the larger tributa- 

 ries of the Ohio. 



The branchial oviducts when inllatcd with eggs, exhibit 

 a series of tubes, which, when dried, appear granulated 

 under the microscope ; these tubes are dirty yellowish, 

 with a few blackish spots near their tip ; beyond these 



