152 Proceedings of the Royal Physical Society. 



captured when a small mesh net is used {op. tit.). In view of all this, I am 

 not surprised to find only a small percentage of females among the 2604 

 specimens in Lot U. It is, however, noteworthy that out of 2064 individuals 

 only 76 or 3"7 per cent, are females. In connection with the explanation I 

 have offered as to the preponderance of males found, I transcribe the 

 following from my rough notes made after examining a boxful of specimens 

 sent to the Zoological Laboratory on 26th February 1908: "Specimens 

 small, box only three-fourths full. Of 309 examples, 41 are females. 

 These 41 are so small that it would be very difficult to pick other 41 

 specimens equally small from the remaining 268 individuals." In another 

 box there was only one female among 239 individuals, and in still another 

 box there were only three among 226. Of the combined total of 4491 

 Norway lobsters which have now been examined in the Zoological Laboratory 

 less than 5 - 7 per cent, were females. 



None of the females showed any variation in the number of oviducal 

 openings. My observations therefore do not confirm Cole's 1 statement that 

 in Nephrops " abnormalities in oviducal . . . apertures are by no means 

 uncommon." In each of the 186 females found in Lots B and C, as well as 

 in 703 additional females captured in the North Sea, no abnormality was 

 noted either in the number or in the position of the genital openings. 

 It is remarkable that while few variations occur in the oviducal, and 

 many in the spermatic, apertures of Nephrops, there are many variations in 

 the oviducal, and few in the spermatic, apertures of Astacus. 



Among those individuals examined on 10th May of this year there was 

 found a medium-sized " berried " female, the only example of a " ripe " female 

 among the 76. As it does not seem to be definitely known which is the 

 particular season of the year when the female Nephrops liberates the " eggs," 

 which she has carried for some time glued to her swimmerets, it may be 

 worth recording that I have found " berried " females in the months of 

 October (several examples), February (a few specimens), and one in each of 

 the months of April and May. 



Norway lobsters are known to frequent areas where the sea floor is 

 muddy, and many of the examples had the carapace, legs and abdominal 

 segments partly covered with polyzoa {e.g. Flustra), barnacles, worm tubes 

 {e.g. Serpula and Spirorhis), hydroids {e.g. Scrtularia and Eudendrium), and 

 other creatures, such as small bivalves and tunicates. 



1 Cole, " Some Variation in the Spinal Nerves of the Frog," Trans. Liverpool Biol. Soc, 

 vol. xv. p. 114 (1901). 



