Genital Apertures in the Norway Lobster. 



149 



4. Examples with Five Genital Openings. 



In this collection there are ten examples, each with five genital apertures. 

 These show the following three arrangements : — 



Walking Legs. 



R l . L. 



R. L. 



R. L. 





Third Pair .... 

 Fourth Pair .... 

 Fifth Pair .... 



• 



• • 



• • 



• 



• • 



• • 



• • 

 • 



• • 





Total Num. of Examples 



5 



3 



2 



-10 



Here, as in those specimens with three openings, there must necessarily be an 

 entire absence of bilateral symmetry. The modified anterior abdominal 

 appendages prove the two examples with openings on the third and fifth pairs 



of legs to be males. 



5. Examples with Six Genital Openings. 



This variation occurs in only three specimens, all of which show the same 

 arrangement of apertures — one on each of the right and left legs of the third, 

 fourth and fifth pairs. This is an example of perfect bilateral symmetry. 



6. Summary. 



Though I did not observe an example with seven genital openings, 

 Dv Marshall (I.e., p. 3) found such a specimen in the Zoological Laboratory 

 material in 1901. His example with seven openings had a single opening 

 on each of the legs of the third, fourth and fifth pairs, and also on the left 

 second walking leg. Examples with so many apertures are certainly not 

 numerous. I have previously recorded (I.e., p. 141) an individual with an 

 arrangement of six apertures which was not noticed in this collection. It is 

 referred to here because it exhibits the only arrangement of openings which 

 I had already noted, which has not been again observed amongst those 



1 R. and L. stand for Right and Left sides. 



