REPORT OF THE DIRECTOR AND STATE GEOLOGIST 1901 rl35 



to the second and third maxillipeds of the adult. This zoea 

 swims around in the water near the surface and is eaten in 

 immense numbers by fishes and other pelagic feeders. It molts 

 (probably) six times, with but little change of form, except for 

 the appearance of the walking legs, first as small buds, behind 

 the swimming legs. At the next molt, however, the form 

 changes suddenly, becoming much more crablike, though still 

 differing in several points from the adult. By a further series 

 of molts, the megalops, as the stage is called, gradually passes 

 into the definitive crab form. 



The exact number of molts which the crab takes to attain the 

 adult form is not certainly known, and the different stages have 

 never been described. From a number of observations bv the 

 writer, it seems probable that it takes at least three years for 

 the crab to attain maturity. This agrees with the observations 

 of Mitchill, quoted in the paper by M. J. Eathbun. He also 

 sets the limit of the crab's life at about seven years and states 

 that they do not molt after arriving at maturity. It is certainly 

 true that we do not find such giants among the crabs as we do 

 among the lobsters, but the occurrence of large specimens makes 

 it seem probable that in some cases at least the increase in size 

 continues. 



The female in berry can certainly be regarded as being adult, 

 yet she molts again after the eggs are hatched. This leads to 

 the question, whether the crab, as the lobster, can lay more than 

 one batch of eggs. It is generally assumed that she does not, 

 but the question has not been definitely settled. 



This molting of the Crustacea, shedding it is usually termed, 

 is an operation which in the case of the crab at least adds con- 

 siderably to the commercial value. The shedding is due to the 

 fact that the outside skin of the crab is hard and incapable of 

 growth, so that, as the animal increases in size, it must be cast 

 off. In the crab this is accomplished by the shell of the cara- 

 pace, or body, splitting all around the edge. Then the upper 

 part is raised up, disclosing the body of the crab underneath, 

 covered with the new skin, which is as yet very soft. The crab, 



