36 THE WONDER OF LIFE 



the smaller patches suddenly become animated and crawl 

 away. Another surprise is in store for him when he picks 

 up one of these small patches and finds it to be the cover 

 of a crab carefuUy hollowed out so as to fit the outline of the 

 carapace, and tightly held in place by the last pair of 

 legs, whose dactyU [terminal joints] are hooked into the 

 intumed rim.' 



Mr. Cowles also describes the way in which the Pistol 

 Crab (Alpheus pachychirus) of the Philippines makes its 

 tube of matted Alga-threads. The tubes, which are rather 

 shelters than masks, are often 25 to 30 centimetres long and 

 2 centimetres ia diameter, and one end is fixed to the rock. 

 A male crab placed on a piece of matted Alga turned itself 

 on its back, and using the slender chelate limbs imme- 

 diately behind the forceps, drew the sides of a furrow to- 

 gether and sewed them by a simple stitching. Threads of 

 Alga were drawn from each side into the opposite side. 

 On another occasion a tube was torn into shreds and given 

 to a pair of crabs, who made a coherent tube by next morn- 

 ing. Filaments were entangled on the edges of a sheltering 

 piece of rock and then drawn together. 



' When the Alpheus found a hole in the rapidly forming 

 tube, the slender legs came through, caught hold of the 

 filaments of the Alga, and manipulated them in much the 

 same manner as a man might the thread with which he 

 darns a hole in his sock ; that is, by drawing the edges of 

 the hole together and fastening them.' 



Self-Advertisement. — In great contrast to those 

 animals that walk dehcately, or lie low, or fade into their 

 surroimdings, or put on disguise, there are those that are 

 noisy and bold, fussy and conspicuous — the self-advertisers. 



