﻿136 Proceedings of the Royal Physical Society. 



seasons, to enable one at present to write confidently on this 

 aspect of the question. All that is quite clear is that of speci- 

 mens of Nephrops above 8 or 9 cms. in length, the majority 

 of the larger ones are males. The average of all the males 

 examined is 14*8 cms., while the females average only 10"7 

 cms. If we consider those captured by the large-mesh net 

 only, and they are truly comparable with the " Zool. Lab." 

 specimens taken by the Granton trawlers, we find that their 

 average lengths are higher (15"1 cms. in the males and 11 '6 

 cms. in the females), but the difference in length for the 

 sexes remains about the same. 



The Tables given prove that the female adult is in general 

 less in length than the male, while the experience gained in 

 handling the specimens has impressed upon me that the 

 females are not only shorter, but that they are, as a whole, 

 creatures of a more slender build. 



2. On the Eelative Proportion of Males to Females. 



From Table III. it is seen that the sex of 5894 Norway 

 lobsters was determined. Of this total only 703 were females. 

 This proportion, being scarcely 12 per cent., is sufficiently 

 small to be worthy of comment. Since the relative propor- 

 tions for the various lots are so variable, an examination of 

 the details of this Table does not readily enable one to form 

 any conclusion as to the probable percentage of females in 

 a chance haul, other than the very obvious one that the 

 males in general greatly outnumber the females. It has 

 often been remarked, by those whose duty it is to handle 

 large numbers of Norway lobsters for University classes, that 

 females are comparatively rare. Dr F. H. A. Marshall, for 

 example, has recorded ^ that out of 1068 Norway lobsters 

 sent in to the Zoological Department of Edinburgh 

 University during the summer and autumn of 1901, only 

 68 were females, and in this connection he suggests 

 that it may be that the majority of females had migrated to 

 a greater distance from land than had the males. The great 



1 Proceedings of the Zoological Society, London, January 1902, pp. 2-12. 



