FIDDLER CRAB — HYMAN. 447 



awkwardly and have difficulty in entering the burrows. It is doubt- 

 less on this account that the egg-carrying females remain hidden in 

 the burrows during the day. After dusk, however, they go down to 

 the water's edge with the others when the tide is ebbing. 



While the egg-laden females come out to feed at any time after 

 dusk, there is a very definite time for the embryos to hatch. Hatch- 

 ing always occurs just at dusk — that is, between 7 and 8 o'clock. 

 The mother crab comes down to the water's edge and fans her abdo- 

 men back and forth to aerate the eggs as usual. If the embryos are 

 ready to hatch, however, the* little larvae burst out of the egg shells 

 and at each forward flirt of the abdomen a small spray of young 

 larvae is shot forward into the water. If the female is not dis- 

 turbed, this continues for 15 to 20 minutes until all the embryos are 

 hatched. It is hardly to be thought that the female ever washes the 

 eggs with the purpose of aerating the embryos. It is possible that 

 she is merely trying to rid herself of a burden. On the evening when 

 the embryos hatch, the washing continues for an unusually long time, 

 possibly because the burden on the abdomen is gradually being 

 thrown off. 



In many Crustacea the female molts very soon after her eggs 

 hatch. The old body shell, with the remnants of egg shells stick- 

 ing to it, is shed. Whether such a molt occurs among the fiddlers 

 is not known. Since the crabs molt in their burrows, observations 

 on their moltings are seldom made. It is also known that in many 

 crustacea a new batch of eggs is laid as soon as the old ones have 

 hatched. This may occur after a molt, as in many shrimps, or without 

 a molt intervening, as in the stone crab (Menippe). This has not 

 been determined for the fiddlers either, but it is possible that each 

 crab lays several times during the warmer months, because egg- 

 bearing females are found from early spring until late September. 



HAZARDOUS EARLY LIFE OF THE LARVA. 



The young crab that is suddenly shot from the shelter of its 

 mother's abdomen out into the teeming sea is exceedingly minute. 

 When fully extended it is about a millimeter long, but in swim- 

 ming the body is bent double, so that the swiftly moving larva is 

 only about half a millimeter in length and the same in width. It is 

 just visible to the unaided eye. The structure of the crab larva is 

 so different from that of the adult crab that scientists of the 

 eighteenth and early nineteenth centuries described the larva as 

 an entirely separate genus of crustacea and gave it the name Zoea. 

 Although it was discovered by Thompson in 1835 that the genus 

 Zoea was made up of the newly hatched larvae of various crabs, 

 the name Zoea has been retained to describe all crustacean larvae 



