154 



Cincinnati Society of Natural History. 



sively by an external ligament, at the hinge-line, and that it, 

 too, is a true Palceoconcha. There is no other genus into which 

 either species, with our present knowledge, can be placed, 

 and yet, there may be a possibility that they are not con- 

 generic, though we think it is exceedingly improbable. In 

 an)^ event, Palceoconcha is a good genus, and Palceoconcha 

 faberi is a good species. 



Crania albkrsi n. sp. 



Plate S, Fig. 17, magnified three and a half diameters ; Fig. 

 iS, magnified one and three-fourths diameters ; Fig. 

 lateral view, magnified three and one-fourth diameters. 



Shell small, subcircular or irregularly subquadrate, probably 

 depending in outline more or less upon the object to which 

 it attached. Dorsal valve quite convex or subconical ; apex 

 acute, subcentral, or situated about one-third of the length of 

 the valve from the cardinal line. Surface marked by fine 

 radiating striae, which rapidly increase in number by implan- 

 tation from near the apex to the margin, but which increase 

 in size very little, if any, toward the margin. Our specimen is 

 also marked by a few larger transverse ridges, that may have 

 been produced by the foreign substance to which it attached 

 during its growth or by some other abnormal cause. The 

 radiating striae cross the transverse ridges, and hence con- 

 stitute the normal surface ornamentation. No lamellose lines 

 of growth. 



When this species is compared with Crania leslia, it will be 

 noticed that it is much more convex, and the radiating striae 

 are much finer and more than twice as numerous. Crania 

 Iczlia has been rarely found at the top of the hills at Cin- 

 cinnati, while it is quite common in the higher rocks at Rich- 

 mond and Versailles, Indiana, and in Butler and Warren 

 County, Ohio. The range, so far as known, is confined to the 

 upper 400 or 500 feet of the Hudson River Group. This 

 species is founded on a single very fine specimen, collected 

 by C. L. Faber near the base of the Hudson River Group, at 

 Bold Face Creek, just below Cincinnati, at a range 300 feet 



