1909. | OF THE LIMPET PATELLA VULGATA. 237 
Of 23 limpets collected at the Cloch on October Ist, 19 were 
males and fairly ripe, 3 were females also ripe, and 1 was imma- 
ture, being only 20 mm. in length. 
The breeding-season, therefore, probably lasts from about the 
middle of July to the middle of January. There is much in- 
dividual variation as to the time of ripening, and so it is 
improbable that any single limpet is mature throughout the 
whole breeding-season. While the commencement of the 
breeding-season seems to be ill-defined, its finish is mere 
definitely fixed. 
Dr. J. F. Gemmill, who has examined the gonads of many 
limpets, tells me that he considers the limpet to be ripe from the 
beginning of November to the first fortnight of January. Davis 
and Fleure write (2. p. 59), “the season of sexual maturity is 
the autumn ; Boutan finds it to be about September at Roscoff ; 
at Aberystwyth we think it is somewhat later.” 
According to Fischer (3. p. 867) “la ponte s’effectue sur les 
cotes océaniques de France a la fin de mars et au commencement 
davril,” which agrees well with the observations detailed above. 
It is probable that on our own shores the limpet is ripest during 
the months of October, November and December. <A. similar 
state of affairs seems to hold in the Adriatic, for Patten (8) 
obtained artificial fecundation of the eggs of Patella at Trieste 
in the beginning of December and the middle of January. At 
Naples, however, Wilson found the eggs of Patella cwrulea in a 
mature state from March until June (12. p. 199). | 
Size at which maturity is reached.—From the examination of a 
large number of limpets (80—-90)'T find that sexual maturity is 
reached by the males at a length not less than 21 mm. I have 
found immature males during the breeding-season 16°5, 19°5, 20, 
and 21 mm. long. The gonad grows with the animal, and in 
males 21-30 mm. in length it is only about half its ultimate size. 
It is fully developed at about 40 mm. 
I have seen no female smaller than 26 mm., but at that length 
the limpet may have mature ova. The ovary attains its full size 
in limpets of about 40 mm. in length. 
According to Dr. Gemmill’s observations limpets may be 
mature as small as 18-20 mm. 
It is of interest to compare the closely allied Acmea with 
Patella in this respect. In Aemca (the breeding-season of which 
lasts from the middle of April to the end of July) sexual maturity 
is attained under 10 mm. long and probably after one winter 
(Willcox, 11). 
Another interesting example from among the Gastropoda of a 
very rapid attainment of sexual maturity long before adult size 
is reached is to be found in Semper’s ‘ Animal Life’ (p. 126). 
Land snails in the warm regions round the Mediterranean are 
brought to sexual maturity when only six months old by the heat 
and moisture of the spring. They are then by no means full- 
grown. 
Proportion of the Sewes.—Out of 87 limpets examined, 66 were 
