Hadley, Behavior of the At^ierican Lobster. 255 



pelagic manner of existence and enter upon a more sedentary life 

 among the rocks and weeds of the sea bottom. But this is by no 

 means the case, for never in the life history of the lobster do we 

 find surface swimming more strongly manifested than in the fourth 

 stage, and just after the loss of those accessories without which 

 swimming would have been impossible in any of the earlier stages. 

 The energetic surface-swimming of the fourth-stage lobsters was 

 evident from many observations, made under both natural and 

 experimental conditions. It was observable not only in the large 

 hatching bags but also in the quiet water surrounding the bags 

 and hatching apparatus. One case is especially noteworthy. In 

 July a steam launch, of which the captain lost control, rarqmed one 

 of the floats which suspended six large hatching bags containing 

 lobsters in various stages. As a result many fourth-stage lobsters 

 were suddenly liberated in the water about the hatchery. When 

 order had been restored, an attempt was made to recover the lost 

 lobsters, and over five hundred of the fourth-stage which were 

 swimming actively at the surface of the water were picked up 

 with scrim nets. A far diff^erent phenomenon obtains in the behav- 

 ior of fifth-stage lobsters under natural conditions. This is illus- 

 trated by an interesting sequence of changes in the swimming 

 habits. When the majority of the lobsters in the bags were in the 

 fourth-stage, they usually swam near the surface. As the larvae 

 moulted into the fifth stage, fewer lobsters were to be seen. The 

 reason for this was ascertainable if one poked with a stick about 

 the mass of weeds and algae adhering to the sides and bottom of 

 the bag. Here could be found, carefully hidden, a large number 

 of fifth-stage lobsters. By the time all the individuals in the bag 

 had passed to the fifth-stage, scarcely one could be discovered 

 swimming freely. Whenever a number of fifth-stage larvae were 

 liberated in the open water, it was an interesting sight to observe 

 them swim for a moment, then turning head down, disappear for 

 good in the deeper water — a great contrast to the behavior of the 

 fourth-stage lobsters under similar conditions. 



Another set of observations refers to the burrowing instinct of 

 the young animals. When early fourth-stage lobsters were trans- 

 ferred to glass dishes, on the bottom of which was a layer of sand, 

 gravel and a few broken shells, they at first paid no heed to these 

 conditions, but for several days continued to swim as persistently 

 as ever. Finally, however (usually within two or three days after 



