48 
ORIGIN OF LIFE IN AMERICA 
biological evidence, though it Is usually argued that the ocean 
crept inland through the St. Lawrence or Hudson River 
Valley. 
Fifty years have elapsed since Professor Loven * first drew 
attention to the presence of several crustaceans, allied to 
marine forms, in Swedish lakes, and endeavoured to prove that 
the latter must have been covered by the sea in recent geo¬ 
logical times. One of these crustaceans is the fresh-water 
shrimp Mysis relicta, closely related to the common Arctic 
marine form Mysis oculata. Since the latter does not occur in 
the Baltic, the theory that Mysis relicta is a recent immigrant 
from that sea is untenable. It seems much more probable 
that it gradually developed from its marine relative Mysis 
oculata, when the Arctic Ocean covered the lowlands of 
northern Russia, Sweden and northern Germany. This view 
is confirmed by the fact that Mysis relicta has now been dis¬ 
covered, along with other marine organisms, in several lakes, 
all of which are situated within the area covered by the north 
European drift. I have also alluded to its occurrence in 
Lough Neagh in Ireland.f 
Now it is of great interest that this small fresTi-water 
shrimp Mysis relicta, which is so closely related to a marine 
species, should also occur abundantly in Lakes Superior and 
Michigan. First discovered in the stomach of a Coregonus 
taken in Lake Michigan by Dr. Hoy, it was subsequently met 
with by Dr. Stimpson,^ living in about fifty fathoms of water 
in the same lake. It has since been noticed in Lake Superior 
by Messrs. Smith and Verrill, but in no other of the Canadian 
lakes. This is in so far significant, as neither of these two 
lakes are supposed to have been invaded by the sea in Glacial 
and post-Glacial times. All that geologists acknowledge is 
that the sea crept up the Hudson River and the St. Lawrence, 
as far as the western end of Lake Ontario. The latter and 
Lake Champlain had then a marine fauna, and it is there 
that we should expect Mysis relicta to occur. 
But besides this fresh-water shrimp, another small 
* Loven, S., “ liber einige Crustaceen.” 
t Sckarff, R. F., “European Animals,” p. 155. 
| Stimpson, A., “ Fauna of Lake Michigan,” p. 403. 
