288 ELEMENTARY ZOOLOGY 



solid, and yet thaw out and resume active living. Some 

 lie at the bottoms of deep pools through the colder periods, 

 while many others, such as the minnows, chubs, and 

 other kinds common in small streams, bury themselves in 

 the mud, and lie dormant or asleep through the whole 

 winter. On the other hand in countries where the long 

 intense rainless summers dry up the pools, some fishes 

 have the habit of burying themselves in the mud, which, 

 with slime from the body, forms about them a sort of tight 

 cement ball in which they lie dormant until the rains 

 come. " Thus a lung-fish (called Protopterus), found in 

 Asia and Africa, so completely slimes a ball of mud 

 around it that it may live for more than one season, per- 

 haps many; it has been dug up and sent to England, still 

 enclosed in its round mud-case, and when it was placed 

 in warm water it awoke as well as ever." 



Food-fishes and fish-hatcheries. Most fishes are suit- 

 able for food, though not all. Some are too small to be 

 worth catching or too bony to be worth eating. Some 

 of the larger ones, especially the sharks, are tough and 

 rank. A few are bitter and in the tropics a number of 

 species feed on poisonous coelenterates about the coral 

 reefs, becoming themselves poisonous in turn. But a fish is 

 rarely poisonous or unwholesome unless it takes poisonous 

 food. Where fishes of a kind specially used for food gather 

 in great numbers at certain seasons of the year, fishing is 

 carried on extensively and with an elaborate equipment. 

 Such fisheries, some of which have been long known, are 

 scattered all over the world. Along the shores of the 

 Mediterranean Sea, and on the coasts of Norway, France, 

 the British Isles and Japan are numerous great fishing- 

 places. But " nowhere are there found such large fisheries 

 as those along the northern Atlantic coasts of our own 

 continent, extending from Massachusetts to Labrador. 

 Especially on the banks of Newfoundland are codfish, 



