SOME NEW DEVGNIC FOSSILS 



179 



PTEROPODS 



Hyolithus richardi nov. 



Shell large, tapering gradually ; ventral face flat or slightly con- 

 cave; dorsal face highly arched, siibcarinate axially; apertural mar- 

 gin not produced on either face. Semioval in transverse section, 

 apertural diameter to length as i to 3.5. The shell is slightly 

 arched axially, the margins and the dorsal face being correspond- 

 ingly incurved. The ventral surface is marked by very fine lines 



Hyolithus richardi 



concentric to the slightly reentrant curvature of the margin ; these 

 are not crossed by vertical lines except those of structure, but the 

 axial area may be flat and its boundaries present the aspect of ver- 

 tical lines or depressions. 



The opposite or arched surface bears a series of rather coarse 

 subequal vertical ridges separated by flat and broader intervals. 

 Near each margin is a deeper groove ; obscure concentric striae are 

 also preserved on this surface. The apertural margin of this face 

 is slightly inflected. 



Length of average specimen 35 mm ; apertural diameter 8 mm. 



Lower Devonic. Grande Greve, P. O. 



Hyolithus oxys nov. 



Shell usually larger than the foregoing and relatively much 

 broader, margins tapering more rapidly, surface slightly arched 

 axially. Ventral face gently convex throughout and produced at 

 the margin beyond the opposite face into a semielliptical extension ; 

 dorsal face convex but much less so than in H. richardi, the 



