236 Phylum Arthropoda 



placed in a porcelain dish and dried in an oven for about 12 hours at 

 55-60 C. For feeding, a piece of the dried fish is ground in a glass 

 mortar and a small amount of it distributed throughout the tank. 



Several kinds of fishes were tried. The best results were obtained 

 with mackerel. Besides fish meat, dried and ground hard boiled eggs have 

 been successfully used at the Rhode Island State Lobster Hatchery. 



Care must be exercised to remove the unused meat and prevent the 

 decomposition of the debris and of dead larvae. 



By using fish food and exercising reasonable precautions, the author 

 had no difficulty in rearing the lobsters to the 4th and 5th stages, which 

 were reached in 15-17 days. 



Young lobsters may be fed on various animal food, as for instance, 

 pieces of clam, oyster, crab meat, etc. They should be kept in a tank 

 containing small rocks and a little sand. 



Bibliography 



Herrick, F. H. 1896. The American lobster, a stud}' of its habits and develop- 

 ment. Bull. V. S. Bur. Fish. 15:1. 

 Mead, A. D. 1908. A method of lobster culture. Ibid. 28:221. 



Family astacidae 



A CRAYFISH TRAP* 



IN PONDS and streams where crayfish are abundant they may readily 

 be taken by means of a trap constructed as follows: 



A rectangular box of any convenient size, 16 x 24 inches for instance, 

 is built of %-inch mesh galvanized screen wire. Into one end of this 

 box a removable funnel of like material is fitted. This funnel should 

 project about 8 inches into the box and have a flattened opening about 

 4 inches wide and 1% inches deep. 



In setting the trap it should be placed in shallow water on a sloping 

 bank and partially embedded in the mud or sand so that the bottom of 

 the funnel is even with the bottom of the pond. The rest of the trap 

 extends out toward the deeper water. A dead fish wired securely to the 

 bottom of the trap makes an excellent bait. Attracted by this bait, the 

 crayfish crawl into the trap and seem to be unable to find their way out. 

 A single night-set with such a trap will reward the trapper with at least 

 a water bucket full of crayfish for laboratory use, or for the more im- 

 mediate purpose of providing the camp with an exceedingly delectable 

 breakfast. 



M. E. D. 



* Reprinted, with slight changes, from Science 55:677, 1922, by E. C. O'Roke, University 

 of Michigan. 



