NATURAL HISTORY OF AMERICAN LOBSTER. 
361 
I also gave a record of the molts of eight lobsters varying in length from 5^ to 1 1 % 
inches, and found the average percentage of increase (ratio of increase to total length 
before molting) to be 12.01. Then using the records of the lengths of lobsters reared 
from the first to the tenth stages at the laboratory of the United States Bureau of 
Fisheries at Woods Hole, Mass., the percentage of increase for a total of 246 young 
individuals gave the percentage of increase as 15.3 for each molt. The table follows: 
Table 12. — Actual Length of Lobsters during the First Ten Molts. 
Number of molt or stage. 
Average 
length. 
Extremes in 
length. 
Number of 
lobsters 
examined. 
1 
mm. 
7. 84 
mm. 
7. 50 to 8. 03 
15 
2 
9. 20 
8-3 
10. 2 
47 
3 
ri. 1 
10 
12 
79 
4 
12. 6 
II 
14 
64 
5 
14. 2 
13- 4 
15 
15 
6 
16. r 
15 
17 
12 
7 
18. 6 
18 
19- 5 
4 
8 
21. 03 
19- 75 
22 
5 
9 
24- 5 
24 
25 
2 
10 
28. 03 
26. 6 
29- 5 
3 
It should be added that the measurements here recorded were not made with this 
problem definitely in view, and are therefore uneven in number, and further that the 
number of young considered in the last four stages are too small to give satisfactory 
results. 
Assuming the average length of the first larva at Woods Hole to be 7.8 millimeters, 
a table was drawn up giving the estimated length of lobsters during the first 30 molts 
as follows: 
Table 13. — Estimated Length of Lobsters during the First 30 Molts. 
Stage. 
Length. 
Stage. 
Length. 
mm. 
7. 84 
vim. 
32. 55 
37- 54 
2 
9. 04 
12 
3 
10. 42 
13 
43. 28 
4 
12. 02 
14 
49. 90 
13. 86 
15. 98 
57- 53 
66. 34 
6 
16 
7 
l8. 42 
17 
76. 49 
8 
21. 24 
24. 49 
28. 23 
l8 
88. 19 
10 
20 
1 1 7. 24 
Stage. 
Length. 
21 
mm. 
135- i7 
22 . 
155- 86 
23 
179. 70 
24 
207. 20 
25 
a 238. 90 
26 
h 275- 45 
27 
317- 59 
28 
366. 16 
29 
422. 21 
30 
c 486. 81 
We called attention to the fact, which has since been verified, that the increase is 
similar from period to period during the larval and early adolescent stages. Accord- 
ing to Hadley ( 126 ), during the first 17 stages, when the young have reached an age of 2 
years and 3 months, the increase per cent is 18. 
The frequency of molting or the stage period was next considered with the follow- 
ing result: We concluded that during their first year, lobsters as a rule molted from 14 
