Fig. 1. The reproductive cycle of Hemigrapsus 
nudus. 
9 
noticeably begins at about the first week in 
May and continues, somewhat slowly at first 
but then increasing in rate, until about the 
middle of June. Less than 1% of the females 
examined were found to carry a second brood 
of eggs. At this time a period of quiescence 
occurs until oogenesis begins again in the fall. 
After the middle of July no trace of egg-bearing 
females could be found at the Titlow Beach 
collecting site, even though several hundred fe- 
males were examined at each bimonthly collect- 
ing trip. 
OOGENESIS: The process of oogenesis prob- 
ably begins while the female is carrying eggs 
of the previous brood attached to the pleopods. 
Of 20 females dissected in the middle of June, 
4 showed no visible development (using the 
technique described above), while the remainder 
showed some slightly detectable development of 
ova within the ovaries. In most cases these 
ovaries were predominantly hyaline or whitish 
in color, but faint orange or reddish ova could 
be observed. These, however, were too small to 
be measured. By the end of September an aver- 
age measurement of 0.25 mm diameter showed 
that considerable ova development had occurred. 
From this point on, development proceeded at 
a regular but slow pace, and by the end of 
November ova averaged 0.36 X 0.39 mm in 
size. From this time on until the time of egg 
deposition there was only a slight increase in 
ova size. There was a gradual change in color as 
the ova developed. In September most of the 
ova were yellow or yellow-orange in color. The 
orange color prevailed until November but 
then showed a gradual change to a deep brown 
prior to egg deposition. 
SEASON OF COPULATION: Many records of 
copulation were made at the Point Defiance 
laboratory from December 18 to the end of the 
month. Copulation occurred both during lighted 
periods and at night. Field records, which are 
few, suggest that copulation occurs under large 
stones which afford suitable room and ample 
protection. Only one period of copulation is 
necessary as this species, unlike H. oregonensis, 
is single-brooded. 
courtship and copulation: The process 
of courtship or copulation has not been de- 
scribed for the genus Hemigrapsus. One com- 
plete account is recorded by Hiatt (1948:199) 
