Raymond : Bkachiopoda and Ostracoda of thf. Chazv. 2')1 



chell and Schuchcrt, and is probably congeneric with it. The stria." 

 are altcrnatinp; in size as in Rafinesquiua, l)ut the transverse form and 

 the geniculation are like Leptcrtia. Some of the larger specimens show 

 fine concentric wrinkles on the oars of the pedicle \al\e. 



Fig. I. Leplaena incrassata Hal!. Cardinal, dorsal, and ventral view of a 

 small specimen to show deltidium, pedicle opening, and surface markings. X2. 

 Fig. 2. Similar views of another specimen of the same species. X2 



Description. 



Shell transxerse, concavo-convex, abruptly deflected in front. In 

 young stages the shell is plano-convex, not deflected in front, and the 

 outline is sub-circular. In the adult the shell is wider than long and 

 regularly rounded in front. The width at the hinge is not quite equal 

 to the greatest width. The surface is marked by from twenty to thirty 

 strong striae, between which are very fine stria?. On partially ex- 

 foliated shells all the stria? seem to be of equal size. These striae 

 are crossed by fine concentric lines which are about the same size as 

 the stria? and thus give to the surface a pitted appearance. On the 

 ears of mature shells there are fine concentric wrinkles. The delthy- 

 rium, which is wide, is covered by a convex deltidium, but there is a 

 large pedicle opening at the apex. This passage remained open through- 

 out the life of the animal, and usually encroached upon the beak. 



The interior of the brachial valve shows a large, deeply bifurcated 

 cardinal process, the groove between the elements of which is so deep 

 that the two parts seem entirely separated. This groove extends 



