THE AMERICAN LOBSTER. 



187 



The yolk of bard-boiled eggs, crushed crab, boiled liver, tow-net material, Doctilucae, 

 copepoda, and live shrimp larva', were all partially, but none absolutely, successful as 

 a food supply. 



The self-destructiveness of the young lobsters when too closely crowded in aquaria 

 has already been referred to. When one lobster attacks another under these con- 

 ditions the pursuer usually endeavors to get astride of his victim and nip into the 

 abdomen at its junction with the carapace with its sharp-pointed prehensile legs. 

 When the object is too heavy to float, such as the egg or larva of the lobster, they 

 frequently go to the bottom; but if the animal is healthy it will be usually seen swim- 

 ming about the aquarium dragging its prey with it and feeding upon it as it goes. 



HELIOTROPISM OF LARVAL LOBSTERS. 



During the past six summers which I have spent at Woods Hole, 1S89-1894, 1 bave 

 been struck with the scarcity of the larvoe of the lobster in the waters of Vineyard 

 Sound. The tow net has been frequently used both by day and night, and 1 have 

 made many unsuccessful trips in search of young lobsters in the season when one 

 would expect them to be common. Thus, on July 11, 1891, 1 towed all around Gay 

 Head, a mile beyond the Devils Bridge buoy, and in Vineyard Sound. We found 

 only copepods, sagitta, young fish, and fish eggs. The day was bright and the water 

 had been calm for two days. The prevailing winds had been from the northeast. At 

 Menenisha we obtained one lobster with eggs hatching out, but the fishermen reported 

 that very few lobsters with old eggs were then taken; that is to say, the hatching 

 season was about over. 



I had a similar experience on July 1G. The water was smooth; the wind had 

 been southwesterly for four or five days. There was very little surface material, a. 

 few barnacles, megalops and sagittas. 



The following is a list of all the lobsters taken at the surface of the ocean during 

 the six seasons mentioned — the capture was made in the daytime unless otherwise 

 stated : 



Date. 



Observations. 



July 9,1889 

 July 8, 1890 

 July 9,1890 

 July 16,1890 



July 24,1890 

 July 28,1890 

 Aug. 23, 1890 

 July 1, 1891 



June 29, 1892 

 June 29, 1892 

 Aug. 15, 1892 



One lobster (fourth or fifth stage) at surface of harbor. 



One lobster, length 15 mm.; captured with tow net, in harbor, in the evening. 



Five lobsters, 15 to 16 mm. long; taken by R. P. Bigelow aboard the Grampus, at station 32.' 



Two lobsters in sixth stage, 16 niiu. long; taken with dip net close lo wharf of U. S. Fisli 



Commission Station. 

 One lobster. 16 mm. long; taken with tow net in harbor. 

 One lobster, 15 mm. long; taken with tow net in harbor. 

 One lobster, 16.5 mm. long; taken with tow net in harbor. 

 One lobster in sixth stage, 18 mm. long; taken at surface 7 miles southwest of No Man's 



Land. 

 One lobster in third larval stage; taken at surface, near wharf. 

 One lobster in fourth larval stage ; taken at surface near wharf. 

 Young lobsters, probably in fifth and sixth stages, seen at surface of Vineyard Sound by 



Professor Libbey. 



* Location, latitude 41° N., longitude 71° 9' W. Observations made by Professor Libbey, July 12, 1890, 

 10.47 a. in. Surface temperature 63.8° F. ; bottom temperature, 54.1° P. 



Larvne in the first stage have been taken in Vineyard Sound as early as June 3. 

 Lobsters in the fourth stage were captured by Vinal N. Edwards, August 12, 1S87. 

 Young lobsters (stages not determined) were also taken by him in Woods Hole Harbor, 

 Vineyard Sound, and in the vicinity of Gay Head, in the mouth of July, 1888. 



