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Show 1902.] VARIATION IN THE NORWAY LOBSTER. were all obtained from the area of the Firth of Forth. In addition to these I procured 80 specimens which were caught off the Isle of Man. Of these two were females, one was an abnormal male having two pairs of genital apertures, and the rest were Text-fig 3. Diagram illustrating variation in genital apertures in Nephrops norvegicus. Percentage-curve illustrating variation in the number of genital apertures in 1000 male specimens of Nephrops norvegicus. The lower figures give the number of apertures and the side figures the percentage of individuals. normal males. The number is, of course, not large enough for any definite conclusions to be based upon it; but in view of the fact that I never obtained even smaller batches from the Forth area without finding a much higher percentage of abnormality, the presence of only a single abnormal specimen among the Isle |