236 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Professor Powell was good enough to spend three days in showing 
the writer this section, and my interpretation of it differs somewhat 
from that in his published account. The cherty magnesian limestone 
at the base (zone 1) appears to belong to the Beekmantown, not the 
Chazy, and Ophiletas were found in the upper beds. Zone 2 is a fine- 
grained buff limestone with numerous gastropods and some trilobites. 
At the base is a conglomerate with pebbles of magnesian limestone 
and chert in a caleareous matrix. This formation is to be correlated 
with the Mosheim of southwestern Virginia and eastern Tennessee, 
and that in turn is correlated with the lower part of the Stones River 
of central Tennessee. 
The coarse-grained dark limestone of zone 3 is very fossiliferous, 
some of the genera present being Hormoceras, Amphilichas, Illaenus, 
Isotelus, Orthis, Dinorthis, Plaesiomys, Oxoplecia, Leptaena, Plectam- 
bonites, and Solenopora, besides numerous bryozoans. This fauna 
is much more like that of the Black River of New York than it is like 
any fauna of the Chazy in the typical region, Oxoplecia and Plectam- 
bonites in particular being unknown in the Chazy. On the other 
hand, the fauna is more or less like that of the Holston and Lenoir of 
eastern Tennessee, and these latter formations seem to be of Middle 
Chazy age. The relation of this formation to the one below is exactly 
like the relation of the Leray to the Lowville in New York. The line 
of separation between the dark, impure limestone above and the pure 
light-colored limestone below is a sharp one, and yet the top of the one 
formation and the bottom of the other are combined to form a single 
layer; a so-called “welded contact.” 
The Athens shale (zones 4 and 5) is a dark fossiliferous shale in the 
lower portion, and passes rather gradually into an almost entirely 
unfossiliferous blue limestone above. Nemagraptus gracilis and Didy- 
mograptus occur in the lower part of the shale, while Dicellograptus, 
Climacograptus, and the beautiful synrhabdosomes of Diplograptus 
are most abundant at about the middle. Ampyx americanus appears. 
to begin its range with these latter fossils, being here accompanied by a 
Triarthrus, and extends up into the limestone of zone 5. In the upper 
part of its range, I found it accompanied by Cryptolithus, Robergia, 
and Acrothele. The Athens is plainly equivalent to the Normanskill 
of New York, and the Lower Dicellograptus shales of Sweden. 
Zone 6, the Tellico sandstone, is practically unfossiliferous here as. 
elsewhere. Upon it rests a thick mass of shale with some thin-bedded. 
limestone. This formation is generally called the Sevier in south- 
western Virginia, and has not yet been studied in sufficient detail to 
ae = SS ~~ 
7 
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