228 AMADEUS W. GRABAU 
chronous with the shale, carry a Lowville-Black River—Lower 
Trenton fauna, with some elements (Christiania trentonensis, Ampyx 
hastatus, Remopleurides, Sphaerocoryphe, Cybele, etc.) suggesting 
a geographic connection with the European sea of that time. The 
typical graptolite fauna of the Normanskill includes more than 60 
species in all, though the widely distributed forms are much fewer. 
The more constant and characteristic species comprise: (1) Coeno- 
graptus (Nemagraptus) gracilis; (2) Dicellograptus sextans; (3) D. 
divaricatus; (4) Dicranograptus jurcatus; (5) D. ramosus; (6) Diplo- 
graptus joliaceous; (7) D. angustijolius; (8) Climacograptus parvus; 
and (9) C. bicornis. Of this list, Nos. 1, 2, 4, and 8 are the most 
characteristic index fossils of this zone. Didymograptus sagitticaulis, 
Gurley, and Climacograptus scharenbergii, Lapw, may also be men- 
tioned as characteristic though less widely distributed forms. 
Besides the numerous localities along the Hudson and St. Law- 
rence valleys, this fauna is known from Maine and New Brunswick. 
In the Appalachian region it is definitely known only from New 
Jersey and from Bebb County, Alabama; it is also doubtfully identi- 
fied from western Virginia and eastern Tennessee. It has been found 
in Arkansas and the Ouachita Mountains of Oklahoma; in southern 
Nevada (Belmont and Letson peak); and in the Kicking Horse Pass 
of the Rocky Mountains of British Columbia. It is also known from 
New South Wales and Victoria in Australia; and from southern 
Scotland, Scania, and France. 
The distribution of this fauna is such as to suggest an eastern 
and a western land mass (Appalachia and Rockymontana) of low relief, 
with currents of the Gulf Stream type sweeping along their inner 
borders and distributing the graptolites, which became entombed 
in the muds that accumulated in these channels of moderate depth. 
The division of what was probably a single great current, sweeping 
north along the South American coast, and carrying the graptolites 
from Australia, was probably due to the existence of an Ozarkian 
island or Archipelago, along the borders of which, as in Arkansas 
and Oklahoma, were deposited some of these black muds. One arm 
of the divided current swept along the east coast of Rockymontana 
to the Arctic Sea of Alaska; the other along the west coast of Appa- 
lachia, past a Newfourdland island, and across the North Atlantic 
