THE MOLLUSCA 



1017 



163 (164) Male and female shells not greatly different, the latter being some- 

 what more inflated and expanded in the post-basal region. 

 Shell thin, rather compressed, and winged on the dorsal 

 slope; hinge complete, but the pseudocardinals are reduced 

 to mere tubercles often nearly wanting. Marsupium as 

 in Froptera. Glochidia semicircular, very small, without 

 spines Paraptera Ortmann. 



This genus in shell characters is very like the preceding, but has been separated on account 

 of the great difference in the shape of the glochidia. The type, and only species yet known to 

 belong to it, P. gracilis Bar. (Fig. 1525; X |), has a wide range from the Great Lakes south to 

 Alabama and west to the Mississippi Valley. 



164 (141) Male and female shells different, the latter being swollen in the 

 post-basal region. Marsupial characters unknown. Shell 

 short-elliptical, solid, much inflated; pseudocardinals divided 

 into irregularly radiating, granular laminae; hinge plate 

 reduced to a mere rounded line behind the pseudocardinals. 



Glchuld Conrad. 



The type and only species, G. rotundata Lam. (Fig. 1526; X h), ranges from Florida to eastern 

 Texas. Conchologically very distinct by reason of its peculiar hinge, little is known of its 

 anatomical characters and further information is greatly to be desired, especially in regard to 

 the gravid female. 



iiJ'V 



Fig. 1526. 



