362 
BULLETIN OF THE BUREAU OF FISHERIES. 
to 17 times, and attained a length of from 2 to 3 inches, with the probability that this 
limit was often extended. Examining all the data available at the time we further con- 
cluded that the 10-inch lobster was between 4 yi and 5 years old, the higher degree of 
probability favoring the smaller number, and had molted from 25 to 26 times. “The 
reader is reminded,” we then added, “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.” 
The words just quoted were written in 1894; twelve years later the problem of 
the rate of growth in the lobster was taken up by Hadley ( 126 ), who has given an 
excellent discussion of the question in all its bearings and has supplied many of the data 
which were then lacking. His work was conducted at the Wickford hatchery of the 
Rhode Island Commission of Inland Fisheries under conditions which the experience of 
many years and of many workers has brought to a high degree of perfection. His 
results are therefore more complete and more valuable than those of any previous 
students. 
Hadley’s final conclusions (see 126) so far as general results are concerned do not 
differ greatly from those reached by me in 1895, as may be seen by the following com- 
parisons: Thus, I estimated that a lobster in the first year of life molted from 14 to 17 
times, and reached a length of from 2 to 3 inches; Hadley determines that the yearling 
molts 1 2 times and attains a length of 2^8 inches. According to the table (here reproduced 
as table 13) the 10-inch lobster has molted from 24 to 25 times and was estimated to 
have reached the age of 4 yi to 5 years ; according to Hadley a male 9/3 inches long has 
molted 23 times and is 5 years old, while the female of the same length is 1 year and 5 
months older. Thus at this juncture the estimates are from one to two molts apart, and 
for the male in essential agreement as to age. 
Table 14 (after Hadley). — An Estimate of the Rate of Growth of the American Lobster 
from Time of Hatching to Attainment of a Length of 224^ Inches. 
Stage. 
Approximate 
age. 
Length. 
Increase. 
Milli- 
meters. 
Inches. 
metos. I-hes. 
Per cent. 
8. 2 
1 
18 
No. 3. 
8 ! 
iS 
18 
18 
18. 8 
K 
8 
18 
7 A 
3 
18 
18 
618 
18 
iYa, 
18 
8 
18 
No. 13 
1 year 1 month 
62. 0 
2 Yt 
9 
0 
18 
18 
‘s 6 .o 
18 
No. 16 
2 years 
102 . 0 
. 1 
4TE 
16 
0 
18 
Approximate time 
of molt. 
Stage pe- 
riod. 
Sex. 
June 
do 
do 
do 
July 
do 
August 
.. ..do 
September 
October or November . . 
April 
June 
July 
August or September . . . 
October or November . . 
April or May 
2 days . . . 
4 days . . . 
5 days . . . 
12 days . . 
11 days a . 
12. 5 days. 
14 days . . 
15.5 days. 
21 days . . 
25 days. . . 
5 months. 
1 £ months 
33 days c . 
51 days. . . 
M. F. 
M. F. 
M. F. 
M. F. 
M. F. 
M. F. 
M. F. 
M. F. 
M. F. 
M. F. 
M. F. 
M. F. 
M. F. 
M. F. 
M. F. 
M. F. 
a The fifth stage period is generally shorter than the fourth. 
b For female lobsters bearing eggs, there can naturally be no molt during the period that the external eggs are carried; this is 
at least for n or 12 months. 
c The midsummer stage period is usually the shortest. 
