The Cladodont Sharks. — Claypole. 363 
was experienced over the northern half of North America in 
Lower Cambrian time. The Archean floor, which, whatever 
its origin, had been flexed and broken, cemented, bent, eroded, 
and again flexed and eroded, producing a congeries of inextri- 
cable confusion, and almost baffling all efforts at classifica- 
tion, was widely submerged by the early Taconic ocean. This 
ocean crept upon the primitive continent from the north and 
east. Perhaps it covered it entirely. But we know not what 
lies upon the Archean floor in the interior of the continent 
where later rocks have been deposited and still exist. That 
area is nearly as closely sealed against the geologist as is the 
Archean floor beneath the Atlantic. However, so far as later 
sediments do not now conceal it, the remarkable Taconic-Ar- 
chean contact seems to have been found from the Arctic sea 
to the region of the Laurentides north of lake Superior, and 
from Newfoundland to Minnesota and to the Rocky moun- 
tains. The pre-Taconic floor has also been detected at several 
points in states further south. Not only was this pre-Taconic 
floor buried under the basal Taconic beds presumably 
throughout Canadian territory from the Atlantic coast to the 
Rocky mountains, and in New York and New England, but in 
many places the Taconic strata seem to have been cotempora- 
neously disturbed by volcanic ejections, and to have been in- 
truded at a later date by great volumes of anorthosyte and 
allied basic eruptives. 
[Pal.bontological Notes from Buchtel College. No. lo.] 
RECENT CONTRIBUTIONS TO OUR KNOWLEDGE 
OF THE CLADODONT SHARKS. 
By E. W. Claypole. Akron, Ohio. 
Although the name Cladodus has long figured in the litera- 
ture of paheontology, yet it has been nothing more than a name 
so far as the animal which it represented was concerned. Ap- 
plied to detached teeth it gave us no knowledge at all con- 
cerning their wearers. We knew the peculiar three- or five- 
pointed form of the little, usually black, objects in the stone, 
but all that we could affirm concerning the fish was drawn by 
analogy from the existing sharks. But the recent discovery 
