ZOOLOGY. 31. 
antics, while engaged in a sort of a grotesque wrestle. These 
Craw Fish are eaten by many persons, and considered a great 
delicacy. Trout, and most other kinds of fish, prey upon them. 
They are also taken by the racoon. 
There are several species of Leeches which inhabit our marshes, 
of which the Horse Leech is the largest. There are none of them 
used for medical purposes. 
MAMMALIA. 
In all the various branches of Natural History, there are none 
that have undergone a greater change in this country than the ro- 
dent animals. Among them are found some of the finest fur-bear- 
ing animals known in the world, such as the Otter, Marten, Mink, 
Ermine, Fisher, and Beaver, In the early history of Canada, 
those animals abounded in great plenty, furnishing a large supply 
of pelts, which formed the staple production of the country. Most 
of these animals have long since become extinct. The Beaver, 
that noble monarch of the furred tribe. which furnished food and 
clothing to the Indian, long before the intrusion of the whites, on 
this continent, is, like him, fated to disappear before the advance 
of civilization. In different parts of the country, we still find their 
remains, in the form of extensive beaver meadows ; their lodges 
and dams having long since gone to decay. Having been, for 
the last two years, in the Lake Superior country, where these ani- 
mals still exist in considerable numbers, I have had the opportu- 
nity of studying the peculiar habits and customs of this extraordi- 
nary animal. They display great intelligence in the selection and 
construction of their habitations, and would almost appear to 
bring into action, reasoning powers, rather than instinct. 
The Bank Beaver, are those which have their abode on large 
rivers, where a dam can not be constructed. Such is the case 
with beavers inhabiting the Missouri, Yellowstone, and other large 
rivers. In their migrations, which occur from scarcity of food, 
and other causes, they have been known to travel across the 
country, until a suitable place was found, in which to start a new 
colony ; this is generally on some small stream. 
After taking a survey of the premises, and calculating the 
amount of food it will furnish, they set to work under one who 
is the sole director, first to build a dam, (none of these beavers 
