THE AMERICAN LOBSTER. 



97 



The increase per cent in the growth of larvae is recorded in table 34. Sixty-six 

 molts belonging to more than half as many individuals are tabulated. The average 

 increase per cent in length in stages 2 to 10 varied from 11 to 15.84. The average for 

 stages is 13.67; for individuals, 13.89. These facts seem to warrant the conclusion 

 that the increase percentage in the young is very similar to that of the adult, a result 

 of considerable interest. The average length of the young lobster during its first ten 

 molts is given in the following table. The data are taken partly from table 34: 



Tablk 25. — Actual length of lobsters during the first ten molts. 



Number of molt or stage. 



Average 

 length. 



Extremes in 



length. 



Number of 



lobsters 



examined. 



mm. 

 7.84 

 9.20 

 11.1 

 12.6 

 14.2 

 16.1 

 18.6 

 21.03 

 24.5 

 28.03 



mm. 



7. 50 to 8.03' 



8. 3 10. 2 



10 12 



11 14 

 13.4 15 

 15 17 

 18 19. 5 

 19. 75 22 

 24 25 

 26. 6 29. 5 



15 

 47 

 79 

 64 

 15 

 12 



5 



I 1 



2 



3 



4 . 



5 



6 



7 



8 



9 . 



10 





The rate of growth expressed by the average of lengths in the second column 

 of table 25 implies an increase per cent of about 15.3 instead of 13.67 (the average 

 increase in stages recorded in table 34). Assuming the average length of the first 

 larva to be 7.84 (the average of 15 individuals, table 25), and allowing the increase in 

 length at each molt to be 15.3 per cent of the length before molting, we would have 

 the following series of lengths attained during the first thirty stages. 



Table 26. — Estimated length of lobsters during the first thirty molts. 



Stage. 



Length. 



Stage. 



Length. 



Stage. 



Length. 



1 



mm. 

 7.84 

 9.04 

 10.42 

 12.02 

 13.86 

 15.98 

 18. 42 

 21. 24 

 24.49 

 28. 23 



11 



mm. 

 32. 55 

 37.54 

 43.28 

 49.90 

 57. 53 

 66. 34 

 76. 49 

 88.19 

 101.68 

 117. 24 



21 



22 



23 



24 



25 



26 



27 



mm. 

 135. 17 

 155. 86 

 17D.70 

 207. 20 

 ' 238. 90 

 2275.45 

 317.59 

 366. 16 

 422. 21 

 3486.81 



2 



12 



3 



4 



5 



13 



14 



15 



16 



fi 



7 



8 



17 



18 



19 



20 



28 



29 



30 



9 



10 





1 9.5 inches. 



1 11 inches. 



3 19.1 inches. 



According to this estimate a lobster 2 inches long has molted 14 times ; a lobster 

 5 inches in length, from 20 to 21 times; an adult from 10 to 11 inches long, 25 to 26 

 times, and a 19-inch lobster 30 times. These estimates do not, I believe, go very 

 far astray. We see them practically verified up to the tenth molt by comparing the 

 figures given above with those in the second column of table 25. 



The time interval between successive molts is the next point to consider. The 

 yearling lobster undoubtedly varies greatly in size. A young female lobster already 

 mentioned reached the length of 51.8 mm. by December 10, or when from five to six 

 months old (No. 19, table 33). On the 28th of January 16 small lobsters, measuring 

 from 39 to 83.7 mm. in length, were driven ashore at Woods Hole during a storm. It is 



F. C B. 1895—7 



