22G BULLETIN OF THE UNITED STATES FISH COMMISSION. 



noticed a mass of whitish eggs in one of our aquaria inhabited by three 

 adult specimens of Amiurus albidus, two of which were unmistakably 

 the parents of the brood, for the reason that they did not permit the third 

 one to approach near the mass of eggs which one of them was watch- 

 ing vigilantly. One of the individuals remained constantly over the 

 eggs, agitating the water over them with its anal, ventral, and pectoral 

 fins. This one subsequently proved to be the male and not the female, 

 as was at first supposed. The female, after the eggs were laid, seemed 

 to take no further interest in them, the whole duty of renewing and 

 forcing the water through the mass of adherent ova devolving upon 

 the male, who was most assiduous in this duty until the young had 

 escaped from the egg membranes. During all this time, or about a 

 week, the male was never seen to abandon his post, nor did it seem that 

 he much cared even afterwards to leave the scene where he had so faith- 

 fully labored to bring forth from the eggs the brood left in his charge 

 by his apparently careless spouse. The male measured 15 inches in 

 length, the female a fourth of an inch more. 



• The mass of ova deposited by the female in a corner and at one end 

 of the slate bottom of the aquarium measured about 8 inches in length 

 and nearly 4 inches in width, and was nowhere much over one-half to 

 three-fourths of an inch in thickness. The ova were covered with an 

 adhesive but not gelatinous outer envelope, so that they were adherent 

 to the bottom of the aquarium and to each other where their spherical 

 surfaces came in contact, and consequently had intervening spaces for 

 the free passage of water, such as would be found in a submerged pile of 

 shot or other spherical bodies. It was evident that the male was forcing 

 fresh water through this mass by hovering over it and vibrating the 

 anal, ventral, and pectoral fins rapidly. There were probably 2,000 ova 

 in the whole mass, as nearly as could be estimated. All of those left 

 in the care of the male came out, while about one-half of the mass 

 which he had detached from the bottom of the aquarium on the third 

 day, during some of his vigorous efforts at changing the water, were 

 transferred to another aquarium, supplied with running water, and left 

 to themselves. Those- which were hatched by the artificial means just 

 described did not come out as well as those under natural conditions. 

 Nearly one-half failed to hatch, apparently because they were not agi- 

 tated so as to force fresh water through amongst them and kept clean 

 by the attentions of the male parent. 



The eggs themselves measured about one-sixth of an inch in diam- 

 eter a short time after oviposition, and after the large water space had 

 been formed around the vitellus, between the surface of the latter and 

 the egg membrane. The vitellus measured one-eighth of an inch in 

 diameter. The germinal disk was formed at the upper pole of the vitel- 

 lus immediately after oviposition, and gradually spread in the usual 

 manner over the lower pole of the opaque granular vitelline globe. In 

 the early part of the second day the body of the young fish was out- 



