HELODONT TEETH AT ROCHE MIETTE, ALBERTA 
19 
Helodus is an upper Devonian, Subcarboniferous, and Carbon- 
iferous genus, to which has been referred a number of detached, 
anterior teeth which have been given provisional specific names 
and which are generally regarded as belonging to Cochliodont 
sharks. It first appears, on this side of the Atlantic, in the 
Chemung (upper Devonian) of Pennsylvania, but is better 
known from over a dozen species from the Subcarboniferous of 
the central States (Iowa, Indiana, etc.) and is sparingly repre- 
sented in the Coal Measures of Illinois. The genus was origin- 
ally described from the Carboniferous of Great Britain, where 
the limestone series and the Coal Measures have furnished 
material for a number of species. 
The Roche Miette specimen differs in form from hitherto 
described teeth referred to the genus Helodus. It distantly 
resembles H. gibberulus , Agassiz, from the Carboniferous lime- 
stone of Britain, a species which is recognized as having a 
Devono- Carboniferous range in the United States. The genus 
is new to Canada. In the Roche Miette tooth there are incipient 
lateral cones; in H , gibberulus these are highly developed. 
Small, polished, pitted teeth writh a subsidiary tubercle on either 
side of a tumid, subconi cal, central dome, stated by Newberry 1 
to be indistinguishable from H. gibberulus of the British Isles, 
occur in the Chemung and Waverly of Pennsylvania and in 
the Mountain Limestones of Illinois and Indiana 
As the fish tooth from the summit of Roche Miette is appar- 
ently not referable to any described species of the genus to 
which it is considered to belong, and as this genus ranges from 
the Chemung up into the Coal Measures, there is no evidence 
supplied by the fish tooth in question as to the exact age of the 
rocks at the summit of Roche Miette, whether they are upper- 
most Devonian or belong to a higher horizon. The inverte- 
brate fossils, however, which occurred with the fish tooth, have 
been studied by Dr. Percy Raymond of this Survey, who pro- 
nounces them to have a general upper Devonian aspect. This 
opinion, as to the age of the beds, is concurred in by Mr. Dowling 
on stratigraphical grounds. 
ir The Paleozoic Fishes of North America, Vol. XVI, Monographs of the U.S. 
Geological Survey, 1889. 
24855-2 
