366 
bulletin of the bureau of fisheries. 
While we can not make direct comparisons with confidence without knowing the 
number of individuals in each case concerned, figures which neither Smith nor Hadley 
give, I am inclined to believe that while the rate of growth for Woods Hole lobsters 
during their earlier stages may be greater than 15.3 it is less than 18 per cent, and that 
while my former estimate of the age of a lo-inch marketable lobster to be from to 5 
years may need the addition of a plus mark, especially in the female, it is probably not 
far from the truth. 
Female lobsters are found bearing eggs for the first time when measuring from 7^ 
to 12 inches (18.5 to 30.5 cm.). Amid limits so wide it is impossible to say at what 
time the average female lobster reaches the reproductive age, but it is probably not far 
from the lo-inch length, which according to Hadley would represent the twenty-third 
molt and an age of about 6% years. We have no data upon the time of sexual maturity 
in the male, but should expect that it would be reached at the same or at a slightly 
earlier period. 
Regarding the questions of rate of growth in Homarus gammarus of Europe, I shall 
give the general conclusions of Ehrenbaum (Sj ) , whose studies at the Helgoland laboratory 
are well known : 
It is possibly not superfluous at the end of these observations to state again clearly that the results 
which the American naturalists and we in reliance upon them have reached in regard to groudh and the 
relations between size, age, and life-stage cannot be regarded as completely reliable. 
The numerical results which are given in the works referred to and which have been partly repro- 
duced, can in the most favourable cases be regarded as of only average value, especially when we reflect 
that all biological relations possess a certain variability and cannot be expressed in absolute figures. 
If, moreover, we reach the result that the Helgoland lobster lays her eggs for the first time in her 
seventh year of life, it by no means contradicts the idea that in many individuals this may happen 
in the sixth year, while occasionally females of only 23 centimeters {g^ in.) in size have been observed 
with extruded eggs, and moreover it may happen that in single cases the first egg-laying is delayed 
until the eighth year of life. 
But even disregarding this natural and anticipated variability, it cannot be denied that our figures, 
even as averages, possess a certain untrustworthiness, since only one element rests upon direct observa- 
tion, while another is based upon combinations. This uncertainty is sufficiently reflected in my earlier 
contributions (see communication of 1903, p. 154), wherein I came to the conclusion that female lobsters 
were in their sixth year of age when for the first time they carry eggs, while now, standing upon a basis 
not much more extended, I have accepted the seventh year in preference. 
Moreover the American authors waver between the sixth and seventh year as regards the period in 
question, and find a way out on the supposition that the period is six years for the southerly state of 
Rhode Island, and seven years for more northerly Massachusetts and Maine. Accordingly it is well to 
lay it down as a general rule that the first egg-laying takes place in the sixth or seventh year of life, 
with the higher probability favoring the longer period. This statement would then hold good for both 
American and European lobsters throughout their areas of distribution. Moreover, it can be accepted 
as fixed that this egg-laying takes place in from the twenty-third to the twenty-fourth stage of life. 
