654 THE THORNBACK SPIDER-CRAB. 



The answer to the problem is simply that the creature sheds its ar- 

 mor annually, expands rapidly while yet covered only by a soft skin, 

 and is soon protected by a freshly-deposited coat of shelly substance. 

 Even this answer contains a second problem little less difficult than 

 that which it solves : How can a Crustacean, say a crab or a lobster, 

 shed its skin ? It is true that the cast shells are found, showing that 

 the creature has escaped from its old and contracted tenement by a slit 

 in some part of the body, such as the top of the carapace, and has left 

 its shell in so perfect a state that it might easily be mistaken for the 

 living animal. But how did it manage about the claws? We all know 

 what large muscular masses they are, how very small is the aperture 

 in which the joint works, and how stiff and firm is the broad tendinous 

 plate which is found in their interior. Examination shows that there 

 is no opening on the claws through which the creature might have 

 drawn the imprisoned limb, and it is also evident that the only method 

 by which these members can be extricated is by pulling them fairly 

 through the joints. As a preliminary step, the hard, firm, muscular 

 fibres which fill the claw and give it the well-known pinching power 

 become soft, flaccid, and watery, and can thus be drawn through the 

 coraparatiyely small openings through which the tendons pass from 

 one joint to another. The sharp and knife-like edges of the plates cut 

 deeply through the muscle, which, however, is little injured, on account 

 of its soft consistency, and heals with great rapidity as soon as the an- 

 imal recovers its strength and is gifted with a new shell. In the com- 

 mon edible crab the flesh is quite unfit for consumption during this 

 process, as any one can attest who has attempted to dress and eat a 

 " watery " crab. Yet in some of the exotic crustaceans these condi- 

 tions are exactly reversed, and the crabs are never so fit for the table 

 as while they are soft and shell-less, after the old suit of armor has 

 been thrown off, and before the new integument has received its hard- 

 ening. 



We now come to the Spider-crabs, scientifically termed Maiad^e. 

 A very useful British species, the common Thornback Spider- 

 crab, or Squinado, is plentiful upon our coasts, but is not a very 

 prepossessing creature in external appearance, its body being one mass 

 of sharp and not very short spines, and its whole frame possessing a 

 weird-like and uncomely aspect. 



Ugly though it may be in an artistic point of view, it is one of the 

 most useful inhabitants of the sea, acting as a scavenger for the re- 

 moval of the decaying animal matter that is ever found in the seas. 

 More especially along the shore, where the refuse of mankind, such as 

 unsalable fish and crustaceans, is continually being cast into the waves, 

 the Squinado is found to perform the necessary office of removing all 

 such substances. It is a voracious creature, and, being gifted with an 



