REPORT OF COMMISSIONERS OF INLAND FISHERIES. 155 



thus we can say that he grows by molting, but (except for the gradual inter- 

 articular expansion within the few days immediately following the molting 

 process) never between molts. From the fourth stage on, however, each suc- 

 ceeding stage period is of longer interval and the changes which the adoles- 

 cent lobster undergoes are correspondingly less distinct or significant, being 

 characterized chiefly by those alterations in internal morphology which are 

 concerned with the reproductive organs as the young lobster approximates 

 to the adult structural and adult functional type. The slight changes in 

 body form which the older lobsters experience are evident in the increasing 

 "stockiness" of the body, the increasing relative size of the chelipeds, and 

 (in the case of the secondary sexual characteristics) the broadening of the 

 cephalothorax in the male, or the widening of the abdominal segments in 

 the female for the better accommodation and protection of the eggs which 

 are borne attached to the swimmerets on the under side of the "tail." The 

 first three stages of the lobster are free-swimming stages, but all the activi- 

 ties are without co-ordination or aim. The fourth stage is also free-swimming, 

 but in this case there is co-ordination in movement, and the young lobster 

 swims with directness and purpose, usually at the surface, a phenomenon 

 which is very likely determined by the general positive phototropic reactions 

 evinced in this, but not in later, stages. Sometimes in the late fourth stage, 

 but always in the fifth, the bottom-seeking and "hiding-habit" becomes 

 prominent, and lobsters in aU later stages manifest the characteristic habits 

 of the adult species, namely, the tendency to shun the hght and to seldom 

 wander far from the rocky crevices which they select for their dwelling place. 

 There appear to be, however, certain migrations of lobsters, some of which, 

 according to Bumpus ('99), travel long distances in an incredibly short tune. 

 The migration may be general in its nature and characterized by a flux of 

 lobsters into deep or shallow water at certain seasons of the year. These 

 migrations seem to be influenced by water temperatures. There are, on the 

 other hand, certain peculiar individual migrations, as mentioned above, 

 when often a lobster may cover 15 or 16 miles in 3 or 4 days. For such as 

 these there is no explanation available except the general tendency to wander 

 restlessly about (a phenomenon observable in all the early stages) when once 

 they have been removed from their habitual environs or when their habita- 

 tion has been altered, removed, or destroyed. 



This general absence of a migratory tendency (over great distances) which 

 has also been proved to hold true for most of the tagged lobsters liberated in 

 Narragansett Bay is a significant fact which bears upon the possibility of a 

 depletion of lobsers in certain localities — a subject to be considered on a later 

 page. 



