202 



BULLETIN OF THE BUREAU OF FISHERIES. 



the season and surrounding conditions, such as the nature of the sea bottom and the 

 temperature of the water. By far the greater number of lobsters cast their shells during 

 the months of July, August, and September. The time of shedding, however, varies 

 considerably on different parts of the coast, being from 4 to 6 weeks earlier in some 

 seasons in western Maine than in the extreme eastern section. Shedders are not fit 

 for the market, being lean and watery, and soft lobsters are in a similar condition and 

 will not bear much handling or transportation. Until the shell becomes tolerably hard 

 the soft lobster is easily wounded and killed. Lobsters with very soft shells and those 

 that have been mutilated are often kept in the lobster preserves or pounds until the 

 shell is hardened or the injury repaired. 



Traps set by Mr. Vinal Edwards at fixed points on the rocky bottom in the harbor 

 of Woods Hole, Mass., for a period of 7 months, from December i, 1893, to June 30, 

 1894, were daily hauled and the conditions of the shell of each lobster noted. The 

 significant data thus obtained were as follows: 



Table 2. — Data for Lobsters Examined at Woods Hole, Mass., with Reference to Molting 



Condition. 



Of the entire catch, no lobsters had either recently molted or were preparing to 

 molt; 'j'j of these were males and 33 females. The total number of males was smaller, 

 yet the number of soft shells among them was nearly twice as great as in the other 

 sex. This fact implies that the males molt oftener than the females, which would be 

 an a priori deduction from the greater size which the male attains, or that they molt 

 more frequently during this period, assuming that the distribution of these animals 

 was uniform for the time and place. 



In the fullest sense the molting process consists of two distinct phenomena: (i) 

 The formation of a new shell and (2) the rejection of the old. When once formed the 

 shell admits of no increase in size, since it is a dead structure, excreted by the soft 

 skin below it, and when it is outgrown it must be cast off and give way to a new and 

 larger covering. The new shell is gradually secreted under the old one, and when the 

 latter is discarded the new cuticle is soft and flexible, so that it is easily distended to 

 meet the requirements of growth. The growth of the lobster, as of every arthropod, 

 is thus measured by a series of stages characterized by the growth of a new shell under 

 the old, by the shedding of the outgrown old shell, a sudden expansion in size, and the 

 gradual hardening of the shell newly formed. 



