310 A HISTORY OF FISHES 



Another remarkable fact lies in the manner in which the 

 mussel is able to reciprocate the attentions of the fish. Its own 

 breeding season coincides with that of the Bitterling, and it is 

 in the habit of throwing off its own embryos into the water, 

 where they become attached to the adult fishes and undergo 

 their early stages of development. 



Many of the Cichlids {Cichlidae) protect their eggs by carrying 

 them in their mouths, thus ensuring their safety and perfect 

 aeration at one and the same time. This duty is nearly always 

 undertaken by the mother, and even after hatching the young 

 fry do not leave the shelter of her mouth. Later, they swim 

 about in the water, keeping always within easy reach of her 

 head, and should danger threaten they return to their refuge 

 with extraordinary rapidity. When still more developed, the 

 fry may be observed swimming about in a small shoal accom- 

 panied by the parents, the female generally in the middle and 

 the male circling around them. Most of the Sea Cat-fishes 

 {Ariidae) found on the coasts and in the rivers of North and 

 South America have similar habits, but here it is always the 

 male who undertakes the care of the eggs. These are produced 

 in small numbers, and are of remarkable size, measuring as 

 much as seventeen or eighteen millimetres in diameter in a 

 species growing to a length of three or four feet. The eggs are 

 carried about until hatched, and the unfortunate father does 

 not appear to take any food during this period. Another 

 Cat-fish {Platystacus) , of the rivers of Brazil and the Guianas, 

 exhibits a different method of caring for the eggs, but here 

 the female is entirely responsible for their safety. During the 

 breeding season the skin of the lower surface of her body becomes 

 very swollen and tender, assuming a soft, spongy condition. 

 As soon as the eggs have been extruded and fertilised, she lies 

 on them, presses them into this soft tissue, and each egg becomes 

 attached to the skin by a small, stalked cup, remaining thus 

 fixed until hatched. As soon as this takes place, the skin shrinks 

 to its original size, and the abdomen is once again perfectly 

 smooth. 



Apart from the Sticklebacks, nest building is the exception 

 rather than the rule among marine fishes, and any sort of 

 parental care is very rare. Some of the Wrasses {Labridae) are 

 said to construct rude nests of seaweed, shells, or stones, an 

 operation in which both sexes take part. Many of the Gobies 

 (Gobiidae), Blennies (Blenniidae), Bull-heads or Sculpins (Cottidae), 

 and Cling-fishes (Gobiesocidae) , nearly all of them inhabitants of 



