LIRADISCUS. 



511 



GENUS Hi. LIRADISCUS GREV, 1865. 



a. b. 



Fig. 260. Liradiscus ovalis. 



a. Girdle view. b. Valve view. 



Fig. 261 Liradiscus ellipticus. 



Valves circular or elliptic, convex, sinuous-reticulate, more or less 

 bristling with spines. Connecting zone narrow. 



This genus includes seven curious species, the greater part fossil. 

 Figure 260 representing Liradiscus ovalis Gr., and fig. 261. L. ellipticus Grev. 

 will give an idea of the genus. 



Figure 262 represents Epithelion curvatum 

 Paul., which does not appear to me to be 

 differentiated from a Liradiscus. 



Dr. Pantocsek, in a letter to me of the 26th 

 February, 1894, defines his genus Epithelion as 

 " Frustule oblong, oval, convex, with epithelioid or 

 punctate-spinous structure." 



Fig. 262. Epithelion 

 curvatum. 



