Meyer. ] 136 (March 16, 
quadricostata Say sp., and others. He transmitted to me recently for 
examination some little shells and some sand adhering to some of these 
large shells, in which material the species enumerated below were found. 
Partly they are already known to occur in Yorktown, for their greater 
number, however, they are described from other localities of the Atlantic 
Miocene. <A few forms are new or new to the American Tertiary. 
Some of the determinations were made from the published descriptions 
and figures, but in many cases these are insuflicient for a determination, 
especially as far as the smaller species are concerned. Therefore, fre- 
quently the type-specimens in the collection of the Academy of Natural 
Sciences were compared and especially the forms described by H. C. Lea, 
from Petersburg, Va.,* had to be studied. My thanks are due to the 
Curator in charge of the Academy, Prof. A. Heilprin, who enabled me 
to study a great number of fossil types. Besides, I am obliged to the 
Curator of Molluscs of the Academy, Mr. Geo. W. Tryon, Jr., who gave 
me the opportunity to compare recent material. + 
It is here not attempted to give the ultimate names of all the enume- 
rated species, for this would presuppose a nearly complete working up of 
the Atlantic Miocene paleontology, including a comparison with recent, 
Eocene and European forms. But the opportunity is used at least in some 
cases to unite species, which, in my opinion, are synonyms. The fol- 
lowing list of smaller species from Yorktown, Va., will probably be in- 
creased considerably in future, as the quantity of examined sand was only 
a small one. 
I. SPECIES KNOWN FROM THE ATLANTIC MIOCENE. 
Lamellibranchiata. 
Ostrea sp. (juv.) 
Anomia Ruffini Conr. 
Plicatula marginata Say. 
Lima papyria Conr. 
Pecten eboreus Conr. : 
Arca centenaria Say. : 
Arca carolinensis Conr. 
Pectunculus lentiformis Conr. 
Pectunculus subovatus Say. 
Nucula diaphana H. C. Lea. 
Leda acuta Conr. 
(= Leda carinata H. C. Lea.) 
Yoldia levis Say sp. 
Carditamera arata Conr. 
* Transact. Amer. Philos. Soc., Vol. ix, pp. 229-274. 
+ Since the above was written, Science has lost a valuable worker in Mr. G. W. Tryon, 
Jr., whose death occurred on Feb. § 88. 
