DEVELOPMENT, GELASIMUS AFTER HATCHING 487 



Rearing the larvae. During the summers of 1915 and 1916 I 

 made many unsuccessful attempts to rear the larvae secured by 

 hatching the eggs while they were still on the female. I carried 

 one solitary specimen through three molts, several through two 

 molts, and many through one molt, but the great majority of 

 the zoeae died before their first molt. The only method by 

 which I succeeded in carrying any beyond the first molt was as 

 follows: Small floats, 6 inches by 8 inches by 2.5 inches, with 

 sides of fine bolting cloth, were made. The zoeae were placed 

 in these and these bolting-cloth floats then placed in crab floats for 

 protection from the rippling of the surface water. The difficulty 

 with this method was that debris rapidly collected on the float 

 and clogged its meshes. The bolting cloth rotted quickly and it 

 was difficult to recover the zoeae. 



Larvae from the tow. The fifth zoea and the megalops and crab 

 stages were not reared from the egg. The method of tracing the 

 development through these stages was to collect specimens of 

 some known stage from the tow and keep them in the laboratory 

 until the next molt. The zoeal stages could rarely be kept alive 

 through more than one molt. On the other hand, the megalops 

 and crab stages could be kept alive indefinitely if they were fed 

 and protected from the cannibalistic tendencies of their fellows. 



The stages for study were obtained as follows. The first, sec- 

 ond, and third zoeal stages were abundant in the surface tow from 

 July 1st to September 15th. The tow might be taken anywhere 

 in the harbor or outside. The stages could be separated with 

 some difficulty and placed in glass bowls. The next molt gener- 

 ally occurred in a few days. 



The fourth and fifth zoeal stages seldom appeared in the sur- 

 face tow. These stages, however, could be obtained readily from 

 the bottom tow. The method of towing on the bottom was as 

 follows : A bolting-cloth sac was made to fit inside a small heavy, 

 bottom dredge. This was then dragged carefully along with 

 just enough rope to let it touch the bottom. Care must be exer- 

 cised to keep it from digging. The only successful tows of this 

 kind were taken over a sandy bottom. The best place was found 

 to be along the southwest edge of Bird Island Shoal, 



