


530 OUR COMMON FRESH-WATER SHELLS. 
brought the whole force of workmen to the rescue, otherwise 
he would certainly have made way with one or more; for 
Esquimaux dogs in almost any number, are no match for à 
northern wolf. 
' Of the other breeds of dogs which are used as draught 
animals in the north, I have already mentioned the large 
dogs of the Hudson Bay Company's traders, which are 
known to me only by description. The Indian dogs appear, 
for the most part, like a very degraded variety derived from 
the wolf. A peculiar variety, of unknown origin, but prob- 
ably from Europe or Siberia, was used to some extent by 
the Russians. In appearance it resembles the shepherd dog, 
but stands as high as a Newfoundlander. Its shape is slen- 
derer than that of the native breed, and the hair is shorter, 
the colors are usually black or dark brown and white or tan, 
with a yellow spot over each eye, as in some of the terriers. 
They appear to be.quite as hardy and serviceable as the 
native variety. I have known a team composed chiefly of 
dogs of this breed to travel with a light load over à well 
marked track, between sixty and seventy miles in à single 
day. 

OUR COMMON FRESH-WATER SHELLS. 
BY E. S. MORSE. 

In this and a few succeeding papers we intend to give à 
brief outline of several groups of fresh-water mollusks 
common to the United States. 
The intention is to make them useful to the young col- 
lector in enabling him to determine the generic names of the 
more common shells he may have in his collections, and to 
. give him some idea of their habits and structure. He will 
also become acquainted with the specific names of the mc 
mon shells he meets with. Nothing more than a brief 


