EARLY DEVONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 1 43 



PTEROPODA 

 Hyolithus richardi nov. 



Plate 12, figures 14-17 



Shell large, tapering gradually ; ventral face flat or slightly concave ; 

 dorsal face highly arched, subcarinate axially ; apertural margin not pro- 

 duced 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 correspondingly incurved. The ventral surface is marked 

 by very fine lines concentric to the slightly reentrant curvature of the mar- 

 gin ; it is not crossed by vertical lines except those of structure, but the axial 

 area may be flat and its boundaries present the aspect of vertical 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. 



Locality. Grande Greve. 



Species name. Andre Richard, Jesuit missioner on the Gaspe coast, 

 1661. 



Hyolithus oxys nov. 



Plate 12, figures 10-13 



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 median portion the most elevated and bounded by 

 two longitudinal grooves. Apertural diameter to length of ventral face as 

 I to 2.5 ; of dorsal face as i to 2. The surface is marked only by concentric 

 striae, arched upward on the dorsal face to correspond with the curvature 

 of the margin ; transverse on the ventral face. Average specimens measure 

 40 mm in length and 14 mm in apertural diameter. 



Locality. At Grande Greve and Indian Cove. 



This is a more abundant species than its associate. 



