RATE OF GROWTH OF THE AMERICAN LOBSTER. 237 



may occasionally pass into the twelfth stage before the winter 

 months. Such specimens sometimes manifest an increase of 28 

 per cent, in passing a single stage. These lobsters are, however, 

 usually among those which were hatched early in the season, and 

 are not very common. 



From observations upon the yearling lobsters it becomes ap- 

 parent that the young creature molts on the average of four times 

 during its second year of life. The thirteenth stage is entered 

 some time in July or August, with a corresponding length of 

 62 mm. In the latter part of August he molts for the thirteenth 

 time and now covers 73 mm. The entrance to the fifteenth 

 stage occurs in October of the second year. No further change 

 takes place until the following April ; that is to say that the aver- 

 age lobster passes its second winter in the fifteenth stage, length 

 86 mm. (33/3 inches). By the middle of June we find the young 

 lobster, now approximately two years old, in the sixteenth stage, 

 and with a length of 102 mm. (4^ inches). 



Observations on the molting periods of lobsters over two years 

 old make it apparent that the entrance to the seventeenth stage 

 takes place some time in the late summer of the third year. The 

 lobster generally molts again before the winter months of the 

 same year into the eighteenth stage with a length of 141 mm. 

 (55/6 inches). No further change is experienced until the follow- 

 ing April. 



After the seventeenth or eighteenth stage the percentage of 

 increase at each successive molt undergoes a gradual diminution 

 as the molting periods become less frequent. The amount of in- 

 crease for lobsters about 6 inches in length appears to be in the 

 neighborhood of I 5 per cent. Thus continuing, we find that the 

 young lobster passes its third winter in the eighteenth stage, 

 molts again in the spring (usually in April) and by June, when 

 approximately three years old, has a length of 162 mm. (6^ 

 inches). 



In lobsters of 7 inches and over we find a still smaller per- 

 centage of increase at each molt ; 1 1 or 1 2 per cent, represents 

 with a fair degree of accuracy the average percentage of increase 

 in length for lobsters between 7 and 10 inches. 



Further observation reveals the fact that lobsters over 6 inches 



