294 Annals of the Carnegie Museum. 



lamina of inner gills free from abdominal sac. The mantle-connection 

 separating anal and supra-anal shorter than in Anodonta. 



Type A. ferussacianus (Lea). 



This is practically an Anodonta with concentric beak-sculpture. 

 The general make-up of the shell is much like Anodonta, while the 

 beak-sculpture is suggestive of the Alasmidonta-group, without being 

 so heavy. 



Anodontoides ferussacianus (Lea). 



Numerous specimens of the typical form, as well as of the var. 

 subcylindraceus (Lea) have been investigated, the former from the 

 Ohio drainage in western Pennsylvania, and the Cumberland River in 

 Kentucky, the latter from Lake Erie. 



Bradytictic. The breeding season begins in August and ends in 

 May; discharging specimens were found on May 14. 



Soft parts described by Lea (Obs., X, 1863, pp. 449 and 451), and 

 Simpson (in Baker, 1898, p. 73), but the latter is mistaken with 

 reference to the marsupium of ferussacianus, while the description 

 of that of subcylindraceus (p. 74) is correct. 



Anatomy essentially that of Anodonta, but it should be mentioned 

 that the mantle-connection between anal and supra-anal is only about 

 as long as the anal as well as the supra-anal. The inner edge of the 

 anal is finely, but distinctly papillose. The posterior margins of the 

 palpi are only connected for a short distance, and the anterior end of 

 the inner gill is about half-way between that of the outer gills and the 

 palpi. The marsupium has the same structure as in Anodonta, and 

 the glochidia (Ortmann, 191 lb, pi. 89, fig. 12) are rather small for the 

 subfamily, subtriangular, and about as long as high (0.32 mm.). 

 They have hooks, although Lea (Obs., VI, 1858, pi. 5, fig. 35) figures 

 and describes them as without hooks. 



I find that by a singular oversight I failed to make any field-notes 

 on the color of the soft parts of this species but from alcoholic material 

 and according to my recollection it is grayish white with the foot and 

 the gills inclining to brownish. The marsupium containing glochidia 

 is brown. 



Genus Alasmidon'ta Say. (18 18.) 

 (Simpson, 1900&, p. 666.) 

 Shell elliptical, or generally rhomboidal, inflated, with a well- 

 developed posterior ridge. Disk generally smooth, but sometime!-- 



