Ill THE SERVICE OF TAILS /I 



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. 



