NATURAL HISTORY OP AMERICAN LOBSTER. 



263 



Table 6. — Sequence of Spines in Periods I-IV op Toothed Claws of Adult, and in Periods 

 I-III of Molting Adult and Adolescent Lobsters. 



It will be observed that four periods usually occur between the spur and lock 

 spines; that in ten individuals only seven regular 8-tooth sequences occur; in one there 

 are two, and in four cases none. The disturbances arise from the interpolation of 

 exceedingly small spines, or the tendency to advance to the next progression, which if 

 complete would give 16 spines to the period. The largest number of spines to the 

 single period given in the table is 12, but I have seen a case in which the third period 

 contained 15 spines. 



A fairly regular claw of large size is represented in profile and horizontal projection 

 in figures 12 and 13, the formula of which for the four principal periods is 31 (table 6, 

 no. i), only one of the sequences being in eights, and the spines of the entire armature 

 totaling 48. 



The serration of the dactyl of the toothed claw is more regular than that of the 

 propodus and similar except for the disturbance introduced by the "lock spine" of the 

 latter. Three or four 8-tooth periods usually occur and the sequences are often perfect. 



