MIGRATION AND HIBERNATION. 151 



the effects of prolonged drought (fig. 14). The 

 rivers in which these fishes live for many weeks 

 or months are absolutely drained, and their beds 

 become baked by the burning sun. To escape 

 an otherwise certain death the mud-fish burrows 

 down into the mud, and there tarries till the 

 clouds come again bringing the grateful rain. 

 In burrowing, as soon as the fish has reached 

 a sufficient depth it coils itself up into a half- 

 circle, covering its mouth with its tail. The 

 skin then secretes a quantity of slime, which 

 forms a sort of inner coat- 

 ing to the mud-chamber 

 in which it is now en- 

 closed, and which serves 

 to keep the walls moist. 

 This chamber is known as FlG . i4._ 0u tiine figure of the 



a " COCOOn " from its re- African Mud-fish (Protop- 



, , , , terus annecteus). 



semblance to the cocoons 



of beetles and moths, which, it will be re- 

 membered, are constructed variously of siik, 

 wood-pulp, or earth. While enclosed in their 

 self-made prison numbers are dug out and sent 

 to this country. The writer well remembers 

 assisting Dr H. O. Forbes to release a number of 

 these fishes from their cocoons, at one of the 

 evening conversaziones held during the last meet- 

 ing of the British Association at Oxford. The 

 clods of earth containing each fish, or some- 

 times two, were then more than six months old, 

 and had to be broken up with a saw and chisels. 

 When the bulk of the earth around the slimy 

 case had been removed, the cocoon was placed in 

 a tank of tepid water. This rapidly dissolved 



