178 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
A young lobster about six weeks old, raised from the egg, and probably in the 
sixth stage, was light brownish-olive on the upper surface, the chelae being more 
decidedly brown. The under surface of the body was almost colorless. The usual 
cream-colored or white spots occurred ou the carapace and appendages and the ter- 
minal spines of the abdominal pleura were whitish. The large claws, which show no 
special differentiation, are held together in front of the animal as it swims forward. 
Wlieu suddenly disturbed, the young lobster opens its claws, spreads wide its arm- 
like chelipeds, at the same time raising itself into a threatening attitude, ready to 
receive or strike a blow. The iridescent pigment of the eyes is no longer visible. 
Some measurements of parts of this lobster are as follows : 
Mcas urem eu t s . 
Millime- 
ters. 
16 
Length of thoi'ax, including rostrum . 
8 
4 
Length of antennary flagellum 
n 
Length of projioclus of large chela 
5.5 
Lobsters in the fifth stage, which are raised in aquaria, swim less at the surface 
than in preceding stages, going frequently to the bottom of the jars for their food, and it 
is during this and partly in the sixth stage that the pelagic life of the lobster comes 
to an end. It then sinks to the bottom and leads an entirely new life. Its larval 
characters have completely disappeared, and buds of the modified appendages of the 
first abdominal segment have begun to grow out. In locomotion and general habits it 
resembles the adult animal closely, but the final adult condition is only attained after 
a long series of molts, which require, in all probability, from four to five years. 
The sixth stage lasted (in three cases observed) 9, 14, and 18 days, respectively. 
SEVENTH STAGE. 
The seventh stage can not be distinguished by any known characteristics from 
that which immediately precedes and follows. Unless one has watched and recorded 
the molts, it is impossible to say at this or a later period through just how many 
ecdyses the animal has actually passed. The larval stages merge insensibly into 
those of the adolescent period, and these pass as gradually into those of the adult, so 
it will be more profitable to follow the history of individual lobsters from this period 
onward rather than to attempt to describe stages which have no marked distinguishing 
characters. 
In table 34 I have recorded the molts of thirty-nine young lobsters raised during 
the summers of 1891 and 1892. The increase at each ecdysis and the increase per cent 
(that is, the ratio between the actual increase and the former length) are also given. 
Many of the adolescent lobsters, which it should be understood are the remnant of a 
much larger number which I attempted to raise, died shortly after the last recorded 
molt. Some, however, were living when I was obliged to leave Woods Hole, at the 
middle or latter part of August, and doubtless could have been reared had they 
received the necessary care. The life-history, as illustrated in table 34, has been 
followed from the time of hatching to the tenth stage or ecdysis, when the animal 
is over an inch long and about three months old. 
We have considered in detail at the close of Chapter m the bearings of these 
observations upon the rate of growth in the lobster. 
