REPORT OF COMMISSIONERS OF IXLAXD FISHERIES. 77 



oviducts, which appear on the basal segment of the first and third 

 thoracic limbs, respectively. 



Seventh to Tirelfth Stages. 



The changes in form which occur between these stages probably 

 depend very much upon the vitality and general condition of en- 

 vironment of the young lobster. Thus the impossibility to attribute 

 to any one of these later stages definite characteristics in form. The 

 most that can be stated is that some features of development appear 

 to be manifested at about a certain stage. Thus the external repro- 

 ductive organs, if they do not appear in the sixth stage, do appear in 

 the seventh. In this and the following stages the difference in the 

 large claws becomes more and more evident. It may be said that 

 the lobster assumes the adult structural type (with reference to ex- 

 ternal morphology) in the ninth stage of its existence. 



Pigmentation and Color Changes. 



In the life history of the American lobster there occur very marked 

 changes in color and coloration. These changes may be grouped 

 under three beads, as follows: 



1. The sudden transitory changes in color (from blue to red, and 

 red to blue) which take place in the first three larval stages. 



2. The more gradual changes in color which a young lobster, be- 

 yond the fourth stage, may experience between any two successive 

 moults; i. e., during one stage-period. These changes are character- 

 ized by a general darkening in color as the stage-period advances and 

 the time of moulting draws near. 



3. The very gradual, progressive change in color and coloration 

 which takes place in the development of the lobster after the third 

 stage, and especially between the third and the twelfth stages. This 

 change is characterized by the slow assumption of mottled olive 

 green and broAvn as the young lobster approximates to the adult color 

 type. 



