Recent Discoveries in the St. John Gro'u.p. 
99 
When we look for a source from which our Lower Cambrian 
fauna may have been derived we are met with the difficulty that no 
other large assemblage of animals of greater antiquity is known. The 
oldest creature known, Eozoon Cmiadense.^ so far preceded in time 
the advent of the Cambrian forms of life, that its influence upon them 
is almost beside the question. It is true that a species resembling 
Eozoon Canadense has been found in the J3re-Cambrian rocks of 
Bavaria, but the genus Eozoon is not known to have left any success- 
ors or nearly related forms in the Cambrian limestones, and may 
therefore be considered as practically extinct at the opening of the 
Cambj’ian period. 
Coming to more recent times than that represented by Eozoon, 
there is a geological stage in Newfoundland indicated by the “Inter- 
mediate Series ” of Mr. Alex. Murray in which a single organism has 
been found. This Intermediate Series is regarded by Mr. Murray 
and others as equivalent to the Huronian System of Canada, and 
therefore intermediate between the Laurentian (the formation con- 
taining Eozoon) and the Cambrian. The organic form which occurs 
in this Intermediate System has been described by the late Mr. E, 
Billings of the Canadian Geological Survey, who appears to have 
thought it a representative of the Gasteropods (Sea-snails, etc.) and 
gave it the name of Aspidella terranovica. It is a curious patelliform 
fossil, which Mr. Billings was unable to refer to any known genus or 
family, so that its bearing on the question of the origin of the 
Lower Cambrian or Acadian Fauna of the St. John Group is some- 
what problematical. 
In the Acadian Fauna of the St. John Group, notwithstanding its 
antiquity, we do not have the ultimate source of Organic Life, but on 
the contrary an assemblage of animals already greatly differentiated 
and adapted to the conditions under which they existed. At the time 
when the Acadian Fauna flourished there must also have been other 
areas on the globe occupied by living beings, for when we consider 
the place and mode of occurrence of the species of the St. John 
Basin, belonging to Division or Series 1, both described and unde- 
scribed, it is clear that there were three successive irruptions of liv- 
ing forms into this area, all of Lower Cambrian type and all strictly 
within the limit upward of the Paradoxidean Zone. Each of the 
three sets of organisms in these beds contains a large proportion of 
distinct species with a smaller number of identical species. The latter 
