98 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



certain that some and possibly all were hatched in the preceding summer. Allowing 

 the lobster (No. 19, table 33) whose length was 51.8 mm. long on the 10th of December 

 to have molted, in case it had lived, three times before the following June, and this is 

 well within the bounds of probability, it would then have attained a length of a little 

 over 3 inches. During the first year the young lobster probably molts from 14 to 17 

 times and attains a length of from 2 to 3 inches, but it is likely that the length reached 

 often exceeds these limits. 



Of the young lobsters recorded in table 32 a few may be the young of the year 

 (JSTos. 1-4), that is hatched in the previous June, but the majority are probably from 

 one to two years old. It is further possible that some of these were hatched at other 

 times of the year than June. 



Brook appears to be the only one who has given a trustworthy account 1 of the 

 successive molts of individual lobsters. He succeeded in keeping a lobster (female, 

 length 6f§ inches) alive in an aquarium 506 days, from July 1, 1883, until November 

 19, 1884, during which time the animal molted four times (on July 1 and December 

 25, 1883, July 25 and November 19, 1884) and increased in length 2- 1 3 6 - inches. During 

 the first year of its captivity it molted twice, in summer and early winter; again it 

 molted in summer and late fall. The lengths at successive stages were as follows: 

 611, 7fV, 8, S\i, 9^ inches. 



In another captive lobster (a male, length 7- x - 6 - inches) four molts were also passed, 

 one in the spring and fall of two successive years (May 19, September 20, May 13, 

 October 13). The lengths at successive stages were as follows: 7- 1 a 6 -, 7-ff, 8^|, 9j%, 9y§ 

 inches. There was an increase here in length of 2-^ inches in 414 days. 



These experiments are instructive in showing that in the unfavorable conditions 

 of life in an aquarium a lobster from to 7 inches long will make a gain in length of 

 2£ inches in 14 to 17 months. It is therefore extremely likely that in nature a 6-inch 

 lobster will often attain the length of from 9 to 10 inches in two years. 



How long a time is the 3-inch yearling lobster growing to become 6 inches in 

 length? Eeference to the series of molts given in table 26, deduced from study of 

 the young, leads us to expect five molts (Nos. 18 to 22) between the 3 and 6 inch stages. 

 It is certain that these do not embrace more than two years, and it is probable that 

 they require somewhat less. We may therefore conclude that a 10-inch lobster is 

 between four and a half and five years old, the higher degree of probability favoring 

 the smaller number. 2 The reader is reminded that this is only an estimate, based, it is 

 true, upon rather slender data, but upon the only facts which we possess. In future 

 years some experiments will be made by which this result can be tested. 



1 Buckland (29) says that " according to some careful observations made at the marine labora- 

 tory, Concarneau, it appears that the first year the lobster sheds his shell six times, the second year 

 six times, the third year four times, and the fourth year three times." If this were ameuded so as to 

 read careless instead of "careful"' observations, no complaint could be made. We have seen that 

 the American lobster molts ten times in the space of three or four months, and it is not probable that 

 the record is very different for the English species. No crustacean is known in which the molts are as 

 numerous during the second year of its life as during the first. A table is also given by Buckland 

 showing the rate of growth during successive molts, but it seems to be based upon error. At the eighth 

 molt the lobster is said to be 2 inches long, whereas the American lobster is less than 1 inch in length 

 at the eighth molt (21 mm., see table 25), and there is no reason to believe that the European species 

 is more than twice as large as its near ally at this stage. 



2 Coste maintained that the European lobster was about 5 years old (length 24 em.) before 

 becoming sexually mature, and this supposition, though unsupported at the time by any detailed 

 facts, seems to be very near the truth. (See 61, p. 285.) 



