182 
GEOLOGY: CLARK, BERRY AND GARDNER 
regions, are separable by the initiation in the Monmouth of a new fauna 
marked by the introduction of Belemnitella americana, Exogyra costata, 
Turritella vertebroides , Anchura pennata, Eutrephoceras dekayi, and prob- 
ably of Liopistha protexta which have been made the basis for the dif- 
ferentiation of the two primary zones shown on the Federal Survey maps 
throughout this region. While it is true that several of the Matawan 
forms persist far into the Monmouth this does not in the last detract 
from the significance of the initiation of a new element of more than 
local importance at the opening of the Monmouth. The time of extinc- 
tion of an old fauna is properly considered as less significant than the 
time of initiation of a new one, and if that new one be sufficiently virile 
to characterize the molluscan life from New Jersey south through Geor- 
gia and west to Texas it indicates something more than a minor oscilla- 
tion in a restricted area and should be given the relatively higher rank 
which it deserves. The Rancocas fauna is very distinct from the pre- 
ceding Monmouth but it is only known in the restricted area of New Jersey 
and Delaware. The same is also true in the case of the Manasquan which 
has an even more limited development in New Jersey. These two later 
formations have no equivalents in the South Atlantic and Gulf areas. 
Correlation. — Raritan. — The Raritan formation of the Middle Atlan- 
tic Coast contains a flora of over 200 species, on the relations of which 
its correlation must be based since but a few uncharacteristic inverte- 
brates have been found in these beds. The Raritan flora has been 
chiefly recorded from New Jersey where the sediments were more fav- 
orable for its preservation than farther southward. It is clearly sepa- 
rable into older and younger florules, the latter making its appear- 
ance in the upper beds near South Amboy, New Jersey, ranging south- 
ward to the Potomac, and reappearing in the lower part of the Tusca- 
loosa formation of the Eastern Gulf and the Woodbine formation of 
the Western Gulf. The Raritan flora is conclusively correlated with the 
Cenomanian stage of the European section by reason of a number of 
forms common to such well-known Cenomanian floras as those of Nie- 
deschoena. Saxony; Moletein, Moravia; Perutz, Bohemia; and Alcantara, 
Portugal. In addition to this considerable element common to the old 
world Cenomanian a large number of identical genera have closely re- 
lated species in the two regions and many new and identical types ap- 
pear at this horizon on both sides of the Atlantic. 
Magothy. — The Magothy formation of the Middle Atlantic coast has 
furnished a rather poor fauna, principally from the New Jersey area, 
and an extensive flora of upwards of 300 species found from Marthas 
Vineyard, Massachusetts, to the Potomac. The Magothy is separated 
