320 
Aug. F. Foerste 
diverging striations, which evidently reproduce the markings on 
the surface of the shell upon which the Crania rested. In addition 
to these striations, this specimen is marked by numerous very 
minute granules which are arranged in an irregular manner but are 
elongated in a radial direction, locally producing the appearance 
of scattered, very short radial striae. In no other specimens are 
these minute granules better defined, and hence this specimen C 
may be regarded as most typical of those lower Eden forms of 
Crania which are characterized by the presence of minute granules. 
These forms, probably constituting a single Eden species, have 
been described under various names suggested by surface features 
conditioned by the supporting surface. 
In a fourth specimen, D, 5 mm. in width, sharp, transverse 
striations with finer intermediate striae occur at irregular intervals, 
but there are no traces of granules. 
In a fifth specimen, E, 9 mm. in width, the transverse striations 
are sufficiently broad to suggest that the Crania rested upon a 
Byssonychia. Eight of these striations, or rather plications, occupy 
a width of 4 millimeters. There are also concentric markings but 
no trace of granules. In another Crania upon the same rock frag- 
ment, but without transverse striations, very minute fibrous lines, 
much more minute than the granules and radiating lines mentioned 
in the description of any of the other Cranias from the lower Eden, 
radiate from the strongly excentric apex toward the circumference 
of the nearly circular shell. The latter is 4.3 mm. in width. 
In addition to this, the inner side of one of the valves of this 
Crania, 4.5 mm. in diameter, is exposed. 
In a sixth specimen, F, about 4 mm. in width, there is the same 
irregular alternation of coarser and finer sharp strise as in specimen 
D, suggesting that the supporting shell may have been a gasteropod, 
but there are no indications of minute granules. Another specimen 
on the same rock fragment does not present any cross-striations, due 
to support on a striated shell. As in the case of the nearly circular 
Crania associated with specimen E, the apex is very excentric, there 
are numerous fine concentric striae, and a few traces of exceedingly 
minute fibrous radiate structure of an indefinite character. The 
length of this specimen is 5 mm., the width is 5.8 mm., and, in the 
present flattened condition of the shell, the apex is about 1.7 mm. 
from the posterior margin. 
