MR. F, H. A. MARSHALL ON 



[Jan. 14, 



(7) Females 1 



Noi-mal males 73 



Abnormal males with arrangement B... 4 



Ditto with arrangement 5 



D 3 



Total ... 86 



(8) Normal males 22 



Abnormal males with arrangement B... 1 



Ditto with ari-angement C 1 



D 1 



12 



85 



25 



Total 



25 



Adding all these together we arrive at the following result : — 



Females 68 



Normal males 878 



Abnormal males with arrangement B... 40"^ 



Ditto with arrangement 40 



D 

 E 



F 

 G 

 H 

 K 

 L 

 M 



31 

 2 

 3 

 2 

 1 

 1 

 1 



U 



>122 



>1000 



Grand Total 



1068 



The total number of male Norway lobsters examined being 

 1000 \ the percentage of abnormality occurring among them is 

 shown to be 12*2. The numerical variation in the apertures, but 

 not the variation in their arrangement, I have indicated by a 

 percentage curve (text-fig. 3, p. 7). It is of interest to note that 

 the homo30sis occurs with little regard to bilateral symmetry. 



The relative scarcity of females is worthy of comment. It may 

 be that the majority of them had migrated to a greater distance 

 from land. The 68 specimens that were examined possessed only 

 the normal apertures on the third pair of walking - legs. 

 Dr. Malcohn Laurie, however, tells me of a female specimen in 

 his possession which has two pairs, the additional ones being on 

 the fourth pair of legs. 



The 1068 Norway lobsters which enter into my calculations 



' Since the above was written I have received 24 male Norway lobsters from the 

 Forth area, 21 being normal, one showing arrangement C and another aiTangement 

 D, while a third presented an arrangement not hitherto observed, having apertures 

 upon the left third and right fourth walking-legs in addition to the normal ones, 

 the total number of apertures being four. 



