ADDITIONAL NOTES ON THE (LVMDUIAN OF OAl'E BRETON. 
101 
of elongated, flattened teeth, that articulate with the sockets in th<! 
ventral valve. The margins of the dorsal valve are l>road and rolled 
backward at the edges. 
Sculpture. — This consists of fine, regular concentric ridges that 
occasionally anastomose. There are about eight or ten ridges in the 
space of one millimetre, the ridges being more widely spaced toward 
the margin. 
The largest valves seen was 12 mm. long; valves of 9 mm. 
are common, the height of each valve is about 1 mm. 
Horizon and locality. — In the shales of E. 3/., near the top of the 
Etcheminian at Dugald and Gillis’ Brooks. Frequent. 
This interesting species seems best represented in Europe by A. 
coriacea of Linnarsson, but that species is of the Paradoxides Zone, 
its umbo is further from the hinge line, and the cardinal features are 
different. 
It will be noted that the supposed vascular trunks in this species> 
Acrothele avia and Obolus ( PaUrobolus ) Bretonensis are far removed 
from the margins of the valves. 
Acrothele, sp. 
A' species of this genus occurs in the flags of Division 2 (/; ?) of the 
St. John Group at a cutting on the Intercolonial R. R. at Long 
Island passage, St. Andrews Channel. The material is too imperfect 
to determine the species. 
Xotes on the following table. 
It seems quite probable that when the Acrotheles that have been 
described from the Lower Paradoxides Beds are compared, some of the 
names may be found to be synomyms, there being five species accred- 
ited to the Band c. But it is to be remembered that there are two 
sub-zones in this band, showing considerable differences in the fauna. 
To the lower sub-zone of Paradoxides lamellatus (c J. CElandicus) 
A. granulata and A. cf coriacea are to be assigned, and to the higher 
or sub-zone of P. eteminicus and Conocoryphe Matthewi, the other three. 
As Mr. Walcott’s species are referred simply to Lower Cambrian, 
one cannot compare them closely with the others ; but it seems pos- 
. ( Co)ifhiued at page 404 - ) 
