GASTEROPODA AND CEPHALOPODA OF THE RARITAN CLAYS 
AND GREENSAND MARLS OF NEW JERSEY. 
By Rospert P. WHITFIELD. 
PRELIMINARY REMARKS. 
In offering the following descriptions and illustrations of the Gaste- 
ropoda and Cephalopoda of the New Jersey marl beds to the public and to 
scientific workers in similar fields, it is perhaps only just to add a word of 
apology for the use of such meager material as is here presented, and that 
apology must necessarily be that it is all there is to present, being the best 
material possessed. In studying these remains I have had the same diffi- 
culties to encounter as those spoken of in the ‘‘preliminary remarks” to the 
volume on the Brachiopoda and Lamellibranchiata;’ but in an extremely 
exaggerated form, as the Gasteropods are represented in the several forma- 
tions only by casts, much more exclusively than are the Brachiopods and 
Lamellibranchs, and the Cephalopods largely by fragments. This, how- 
ever, is not the only difficulty encountered, for these casts are far more 
imperfect and consequently more difficult to understand. Among the 
bivalves there is often the chance of obtaining the hinge structure and 
muscular markings from impressions of single valves, and very commonly 
imprints of the exterior show all the essential surface markings. This is 
not the case, however, with casts of Gasteropods, for these usually repre- 
sent only a small portion of the shell, as the apical portion of the spire is 
almost invariably absent, that space not having been filled by sediment 
before the shell was dissolved, and when present having often become solid 
from deposits of shelly matter in these parts during the life of the animal. 
Mon. U. 8. Geol, Survey, Vol. 9, and Geol. Survey, N. J., Paleontology of the Cretaceous and 
Tertiary, Vol. 1, 
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