How /.s- ihe Cambrian d'tvldedf — Matthew. 145 
witli those of ScjuidiiKivia, and here as there, exhiljit a very 
decided palajontological hreak at the suinniit of the paradox- 
ides beds. Hence Dr. Hicks was justified in dividing the 
Cambrian groups of strata into U|>per and Lower, accordingly 
as they were above or l)elow this horizon. 
Having seen how tlie Cambrian faunas are related to each 
other in Europe, we may now examine their succession in the 
eastern half of North America. 
To Mr. C. D. Walcott is due tlie credit of having determined 
the relation of the Olencllus fauna in this region to the rest of 
the Cambrian system. 
The clearest succession of the lower members carrying un- 
mistakable forms of this fauna is that which he has lately 
examined in Newfoundland. Combining the genera found 
there with those of the Champlain and Hudson valleys we 
find the following. 
Olenellus. *Za<'anthoides. 
Mesonacis. *Olenoides. 
* Paradoxides (Shaler) Bathynotus. 
Avalonia (n. gen. not yet described.) 
*Ptychoparia. * Frotypus. 
* Ag rauJos. * Microd iscus. 
*Solenopleura. * Agnostus. 
Of these thirteen genera it will be observed that two-thirds 
pass to the Paradoxidcs beds, and of the remainder, Avalonia 
is not described, and Mesonacis is by Scandinavian pala^on- 
tologists regarded as a subgenus of OleneUuf<. Tliere is thusj, 
a much closer connection between this fauna and that which 
follows it, than there is between the latter and the faunas of 
the Upper Cambrian. Moreover the embryonic and larval 
stages of Paradoxidcs and Olenellus slu>w tliat the genera are 
closely related. 
We have very little knowledge as yet of the way in which 
the Paradoxidcs fauna was related to that which follows it, 
since both in Newfoundland and Acadia the next zone has 
yielded very scanty remains of trilobites. Perhaps the Mt. 
Stevens section where the genus paradoxidcs has been foundf 
will yield the required information. In Newfoundland Mr. 
Walcott has found Olenus, and in the St. John area (Aca- 
tSoc this joiinial vol. in. No. 1. (.Ian. '89.) 
