BULLETIN OF THE UNITED STATES FISH COMMISSION. 1T>9 

 TabU showing the extent of flounder-hatching from March 6 to April 28, 1884 — Continued. 



From 3,850,000 eggs were obtained 1,850,000 young fish, or 48 per 

 cent., which was a somewhat better result than that secured with the 

 cod. Flounder eggs are a little heavier than those of the cod, their 

 specific gravity reaching 1.026, and we might suppose that they were 

 more difficult to manage, especially when the water was too brackish. 

 This, however, did not prove to be true, as they are more hardy than cod 

 eggs and are not so easily destroyed by resting for a while on the bot- 

 tom. An experiment with Slette* and Tungeflyndre] conducted at the 

 same time was equally successful. The period of incubation was from 

 twelve to seventeen days, according to the temperature of the water. 

 There are about 2,400 Skrubbe eggs in a gram, but the number varies 

 considerably with the size of the parent fish. 



Lobsters. — With a view of testing the possibility of developing lob- 

 ster spawn after it was shed, I procured, on the 21st of June, some 

 lobsters, which were kept in a box in the hatching-house after a portion 

 of their eggs had been deposited. 



The eggs, however, were placed in a specially constructed apparatus, 

 which received a uniform water supply from the large reservoir of the 

 establishment, which was pumped full every morning and evening, and 

 during warm weather at noon also. After a space of about fourteen days 

 the shells began to burst, and the young then appeared, surrounded only 

 by the thin internal covering, which is not shed until they are able to 

 swim, or after the first shedding of the skin. Beyond this stage, how- 

 ever, I was unable to rear a single young lobster out of the whole mass 

 of eggs ; they all died, without exception, within four days after they 

 had escaped from the external shell, and before they were capable of 



swimming. 



1 had observed, though, that the temperature of the water exercised 

 great influence on the longevity of the lobsters, and that this was in- 

 creased proportionally as the water became cooler, whereas during 

 very warm days they usually died within twenty-four hours. 



After I had placed a new lot of eggs in the apparatus, on the 1st of 

 August, I attempted to reduce the temperature by the use uf ice; but 



Pleuronectes limanda. 



t Pleuroneotes $olea, fide Molbeck.— T. H. B. 



