2 34 



PHILIP B. HADLEY. 



ditions. The difference in the above percentages he attributes to 

 the unfavorable conditions of aquarium life. Taking this fact as 

 a basis, and assuming the average length of the first stage lobster 

 to be 7.84 mm., Herrick then constructs the following scheme to 

 show the probable relation between the stage and the size of 

 lobsters from the time of hatching through the thirtieth molt : 



'9.5 inches. 



2 inches. 



3 19. 1 inches. 



Regarding the probable frequency of molts, Herrick assumes 

 that a lobster molts fourteen to seventeen times during its first 

 year of life, and that in this time it attains a length of two to three 

 inches. From this and other detailed considerations, Herrick 

 finally concludes that a lobster ten and one-half inches long is 

 between four and one-half and five years old, the higher degree 

 of probability being in favor of the lower estimate. 



The observations made by the writer and others at the experi- 

 ment station of the Rhode Island Fish Commission at Wickford, 

 R. I., though differing to some extent from the results obtained 

 by Herrick at Woods Hole, may serve to throw further light on 

 the rate of growth of lobsters in their natural environment, and 

 give some hint as to the conditions which modify it. 



The record of the rate of growth of the early stages (one to 

 ten) include observations upon several hundred young lobsters 

 whose definite stage and approximate age was, for the most part, 

 known. Individual records were started immediately after the 

 molt from the third to the fourth stage and were carried on as 

 long as either the weather conditions or the term of life of the 

 young lobsters permitted. In most cases the young individuals 

 were confined in separate compartment cars which furnished a 



