1896.] NATURAL SCIENCES OF PHILADELPHIA. 567 



GEOLOGY OF THE MUSSEL-BEARING CLAYS OF FISH-HOUSE, 



NEW JERSEY. 



BY HENRY A. PILSBRY. 



The deposit containing fresh-water mussels of the genera Uriio 

 and Anodonta, situated at Fish-house, Camden County, New Jersey, 

 on the Delaware River, about 5 miles north of Camden, was first 

 noticed, so far as we know, by Professor E. D. Cope, who placed a 

 series of the fossil Unionidce in the hands of Dr. Isaac Lea for de- 

 scription^ in 1868. In Dr. Lea's paper the bed containing these re- 

 mains is said to be "subordinate to the Green Sand >!«*** 

 belonging to that portion of the cretaceous group which furnished 

 * * * * Hadrosaurus Foulhii Leidy," etc' 



The species of Unionidce, twelve in number, were fully redescribed 

 and illustrated in 1886 by Professor R. P. Whitfield,^ who, relying 

 upon the above statement in Dr. Lea's paper, considers the deposit 

 as " from near the base of the Cretaceous series of the State." Pro- 

 fessor E. D. Cope,* in a brief consideration of " The Fresh-water 

 Clays of the Pea Shore," in 1869, gave an excellent section of the 

 beds, which may be consulted with advantage in connection with 

 the present communication. He held that they were " much later" 

 than the Cretaceous, and, in fact, Pliocene ; basing this conclusion 

 largely upon the finding of a large part of the cranium of a horse 

 believed to be Equus fraternus Leidy. The late H. Carvill Lewis, 

 on the contrary, held the Fish-house clay to be "of interglacial 

 age," ^ and this estimate of the age of the deposit is shared by Dr. 

 C. A. White,® who considers the fossils as of post-Tertiary date. 

 This is also, I believe, the opinion of most Philadelphia geologists 

 who have recently examined the subject. 



iProc. Acad. Nat. Sci. Phila., 1868, p. 162. 



' It is diflBcult to account for this statement, which finds no justification in 

 the stratigraphy of the region in question, so far as I can see. 



^ Brachiopoda and Lamellibranchiata of the Raritan Clays and Green Sand 

 Marls of New Jersey, pp. 243-252. 



* Trans. Amer. Philos. Soc, XIV, N. Ser., pp. 249, 250. 



^ Professor Lewis did not, I believe, formally publish this view, but taught 

 it in his lectures at the Academy of Natural Sciences of Philadelphia, synop- 

 ses of which were published in the " Public Ledger," April-June, 1884. The 

 above quotation is from one of these newspaper reports. 



* A Review of the Non-Marine Fossil Mollusca of North America, 1883. 



