THE ACAEA. 597 



The male of this curious fish has a conspicuous protuber- 

 ance on the forehead, wholly awanting in the female and the 

 young. Somehow or other, the eggs of the female are con- 

 veyed into the mouth of the male, the bottom of which is 

 lined by them, between the inner appendages of the branchial 

 arches, and especially into a pouch formed by the upper 

 pharyngials, which they completely fill. They are there 

 hatched ; and the little ones, freed from the egg, are developed 

 until they are in a condition to provide for their own exist- 

 ence. In their head there is a special lobe of the brain, 

 similar to those of the triglas, which sends large nerves to 

 that part of the gills protecting the young, thus connecting 

 the care of the offspring with the organ of intelligence. In 

 this curious cavity of the father's head the young fish are 

 found in all stages of development, — the more advanced, a 

 quarter of an inch long, and able to swim about, full of life 

 and activity. These appear to exist outside the gills, within 

 the cavity formed by the gill-coverts and the wide branchi- 

 ostigal membrane. The eggs remain in the back part of the 

 gills. 



The parent's care does not appear to cease even when the 

 young are fully developed, but he allows them to swim in and 

 out, and try their powers, if not to search for food ; and when 

 danger appears, opens his mouth, when they all swim back 

 again in a shoal, for safety. The natives assert that some species, 

 at all events, are not actually 'developed in the parent's head, 

 but are laid and hatched in the sand, the male and female 

 watching carefully over them ; and that the fjitlicr only takes 

 charge of them when they are hatched, and receives them 

 within his mouth to protect them from danger. From the 

 observations of Professor Agassiz, however, there is no doubt 



38 B 



