﻿I.AMPSirjS -^o 



Length (male) 98, height 70, diani. 42 mm. 



Length (female) 76, height 63, diam. 40 mm. 



IlHnois; Iowa; Kansas; Missouri? Ohio River? 



This is a very puzzling form, the type seeming to connect 

 with the variety, and there are specimens, which seem to stand 

 between the variety and orhicidata. I have seen perhaps a 

 dozen or more specimens, which are fairly typical, and in these 

 the shell is smaller and more inflated than in the variety, and 

 the epidermis is olive and not darker on the beaks as it is in 

 the form I have called grandis. I found the variety fairly 

 abundant in the Illinois River near Utica ; the typical form, 

 which is a rather rare shell, seems to be most abundant in the 

 Mississippi River in the vicinity of Davenport, Iowa. 



Group of Lcimpsilis ligamentina. 



Shell solid, short, evenly elliptical, not greatly inflated, with 

 a yellowish-green epidermis, with broad, usuallv broken, dark 

 green rays; beaks not prominent, sculpture fine, restricted in 

 area; pseudocardinals rather small, stumpy; nacre silvery or 

 rarely pinkish. The female shell is not greatly swollen in the 

 post-basal region. 



Lampsiijs L.IGAMENTINA (Lamarck). 



Shell solid, almost regularly long elliptical, rounded in front, 

 rounded slightly or pointed behind about midway up from the 

 base of the shell, young and adult specimens moderately in- 

 flated, old specimens decidedly swollen, having a low. rounded 

 posterior ridge, slightly gaping at the anterior base ; old shells 

 having a well-developed lunule running through under the 

 beaks; beaks scarcely inflated, low, their sculpture consisting 

 of very faint, doubly-looped, irregular ridges; ligament large, 

 long; surface nearly smooth or marked with rude, irregular,, 

 low, concentric ridges, tawny to pale greenish with broad, 

 rather faint and somewhat broken rays ; left valve with two 

 small pseudocardinals and two remote, rather small laterals ; 

 right valve with two pseudocardinals, the anterior smaller, 

 and sometimes a small posterior third tooth, with one high 



