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Aug. F. Foerste 
horizon from which it was obtained is not known with certainty. 
It was identified by Hall and Whitfield with Trematis punctostriata, 
but that this was an error was pointed out by Schuchert long ago. 
It is referred with some doubt to Trematis fragilis (Ulrich, Amer. 
Geol., 4, 1889, p. 21, 3, p. 378, fig. 6.) on account of its rotund outline 
.and the general absence of pits over the greater part of the shell 
excepting along the postero-lateral margins. 
The specimen used for figure 8, on plate 1, in the second volume 
of the Paleontology of Ohio, cited above, appears to be preserved 
in the American Museum of Natural History, in New York City, 
where it is numbered 1335-2. The anterior outline of this specimen 
is more rounded than in the published figure, although the specimen 
is slightly wider than long. The punctae are distinct only posteriorly, 
near the beak, and thence along the margin of the shell as far as 
the antero-lateral part of the shell. The remainder of the shell is 
smooth. If the anterior margin of the shell were as moderately 
convex as figured, this specimen could be identified as Trematis 
oblata Ulrich, but the more rounded anterior margin favors Trematis 
fragilis. 
Craniae of the Richmond Group 
The Cranias of the Cincinnatian series of rocks offer interesting 
examples of the influence of the form of supporting surfaces upon 
the form of closely sessile species. Often even the more minute 
irregularities of the supporting surface are reproduced in the upper 
valves of the Cranias. 
In such a form as Crania scabiosa, the margin of the upper 
valve is closely applied to the supporting surface, curving up and 
down on crossing each plication or striation. As the enlarges 
in size, the earlier margins of the upper valves are lifted from the 
supporting surface and later margins of these valves extend outward. 
In this manner the details of ornamentation of the supporting surface 
often are reproduced by the surface of the upper valve of the Crania 
with remarkable accuracy of detail. This fact has been known long 
enough to place such supposed species as Crania multipunctata, Cr. 
costata, Cr. asperula, and Cr. alternata among the synonyms of 
Crania scabiosa. The object in calling attention here to these so- 
called species is not to revive the names once suggested for them, 
but to place on record what the types suggesting these names actually 
were, and to let this record stand as an interesting example of the 
