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^ata available at the time we further con- 

 cluded that the lo-inch lobster was between 4.K and 5 years old, the higher degree of 

 probabiUty 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 oi 2yi inches. According to the table (here reproduced 

 as table 13) the lo-inch lobster has molted from z£_to_^5 times and was estimated to 

 have reached the age of 4^ to 5 years; according to Hadley a male 9^8 inches long has 

 molted 23 times and is 5 years old, whUe the female of the same lengfth is i year and 5 

 rnonths 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 op the Rate ot Growth op the American Lobster 

 FROM Time op Hatching to Attainment op a Length op 22^ Inches. 



stage. 



No. I.. 

 No. 2. . 



No. 3. ■ 

 No. 4. . 

 No. s.. 

 No. 6. . 

 No. 7.. 

 No. 8.. 

 No. 9.. , 

 No. 10. 

 No. II. 

 No. 12., 

 No. 13., 

 No. 14. 

 No. 15. 

 No. 16. 



Approximate 

 age. 



3 days 



7 days 



12 days. 



24 days 



35 days 



7 weeks 



9 weeks 



3 months 



5 months 



9 months 



I year 



I year i month 

 I year 3 months 



1 year 6 months 



2 years 



Length. 



MiUi- 

 meters. 



26. 



32. 



37- 



45- 



53 



62. 

 73.0 



86. 

 102. 



jK 

 iH 

 ij< 

 2H 

 2H 

 2^ 

 3H 

 4A 



Milli- 

 meters. 



1.4 

 1.8 



2-5 



2.8 



3- 7 

 4.0 

 55 

 S-9 

 7-1 

 S. o 

 9.0 



II. o 



13.0 

 r6. o 



Approximate time 

 of molt. 



Jmie 



do 



do 



do 



July 



do 



August 



do 



September 



October or November . . 



April 



June 



July 



August or September. . . 

 October or November . . 

 April or May 



Stage pe- 

 riod. 



2 days . . . . 



4 days . . . . 



5 days . . , . 

 12 days . . . 

 II days o. . 

 12. 5 days. 

 14 days . . . 

 15. S days. 

 21 days. . 

 25 days... 

 5 months. 

 1 i months 

 33 days '. 

 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. 



o The fifth stage period is generally shorter than the fourth. 



' 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 1 1 or 12 months. 



« The midsunmier stage period is usually the shortest. 



