INTRODUCTION OF FOREIGN SPECIES. 157 
siderable time immersed in water, and yet, on being 
placed in favorable circumstances, bave been found to 
retain tbeir vitality, and bave matured and produced 
young. Tbey would not be exposed to severer trials 
wben floating upon a log in the ocean, and tbeir cbances 
of surviving would be as good. Logs and trunks of 
trees wbicb bave drifted from a great distance, may 
often be seen upon our sea-beacbes ; and we remember, 
on one occasion, to bave seen Nantasket beacb, at tbe 
moutb of Boston barbor, strewn witb logs wbicb had 
been driven from tbe rivers of Maine by easterly winds 
of several days continuance. 
The hunts of species, and particularly of the intro- 
duced species, are gradually enlarging, and though their 
progress must necessarily be slow, it is susceptible of 
satisfactory proof. Unless of native origin, as we have 
suggested, the time of their introduction must be taken 
to be a period subsequent to tbe colonization of the 
country, which is comparatively a recent date, and yet. 
some of them bave extended oVer a large part of the 
country, as Helix pulchella, and Bvlimus lulmcus, and 
are extremely abundant. Tbe fact that tbe distant 
regions to wbicb these species seem to have extended, 
are in the track of the early French voyagers and col- 
onists, along tbe great Lakes and about the upper Mis- 
sissippi, is quite significant ; and shows that they might 
have been introduced into those parts directly, with the 
effects of the colonists, in the same manner as we sup- 
pose them to have been introduced on tbe Atlantic hor- 
ror,. 1. 41 
