lil THE SERVICE OF TAILS 71 
dom, without going into the region of fable for 
instances, as the old writers used to do when they 
told how the beaver brought mud and laid it, ma- 
son-like, with his tail for a trowel. If this member 
has any part in the beaver’s architecture, it is only 
by the accidental slaps and rubs it may give to the 
muddy structure as the animal swims around it. 
The scaly, vertically compressed, knife-like tail of 
the muskrat would be much better adapted to such 
a service, but the muskrat puts little or no mud 
into its house building. What the stout, scaly, 
spatulate tail of the beaver really does do, is to 
serve as a powerful sculling oar and rudder in 
swimming and diving; and the same is true of the 
muskrat. 
One of the most curious features of that curious 
creature, the king-crab, or horse-foot, of our sea- 
shores, is the flexibly 
jointed, bayonet-like 
spine which forms its 
tail, and has no ana- 
logue elsewhere among 
crustaceans. He only 
acquires it as he ap- 
proaches adult age, so that it is, as Lockwood 
expresses it, “a sword of honor,” betokening the 
end of youth. Whether or not this sharp rapier 
is of value as a weapon nobody seems to know, 
but it certainly makes a capital alpenstock. The 
horse-foot is light, and is liable, by the least agita- 
A HORSE-SHOE CRAB, USING ITS 
TAIL (TELSON) AS A LEVER. 
