24 
EOCENE TEREBRATULA 
this combination is much more distinctive than those of many 
Tertic species commonly accepted as valid. Although Terebratula 
harlani, in its general features, bears a close resemblance to T. 
marylandica the line between the two species is not difficult to draw. 
According to Greger, T. regitolii Meneghini from the Italian Mio¬ 
cene has an exactly similar pedicle region in size, shape and posi¬ 
tion; microscopically the punctse are similar in both size and ar¬ 
rangement, but are somewhat more widely spaced in the younger 
form. 
In New Jersey, Delaware and the Eastern Shore of Maryland 
Terebratula harlani is associated with it a large fauna, no ele¬ 
ments of which are found in the Eocene sediments. It is likely 
that if this form were a survival of Cretactic times, some of the 
other associated forms would have accompanied it, though not nec¬ 
essarily so. It is not necessary to enumerate here all the genera and 
species occurring in the Rancocas formation, but the following 
enumeration gives idea of the profusion of the life during that 
time. 
Species 
Protozoa . 46 
Echinodermata . 16 
Brachiopoda . 5 
Bryozoa . 54 
Vermes . 1 
Pelecypoda . 17 
Gastropoda . 3 
Crustacea . 2 
Anthozoa . 2 
146 
The fauna of the Rancocas beds of Delaware is similar to that 
of New Jersey. In Maryland the Rancocas formation is unrep¬ 
resented except in one spot near the Delaware boundary, and the 
New Jersey faunal zones cannot be traced into Maryland. 
The Eocene beds of Maryland, as well as of adjoining areas, 
were described by Darton as the Pamunkey formation; they are 
now regarded as representing two distinct terranes, the Nanjemoy 
beds and the Aquia greensands. 
The Aquia formation, which carries Terebratula marylandica, 
consists for the most part of greensand and greensand marl. The 
