13 
Brachyura and Anomura of Puget Sound — Knudsen 
averaging closer to about 0.40 X 0.38 mm. In 
10 specimens sacrificed in February, 3 had ova 
about 0.20 mm in diameter. 
The ova begin to take on pigmentation as 
development occurs. During October most of 
the ovaries were hyaline, while the one indi- 
vidual showing some development had ova of 
a rusty brown color. Generally the transition in 
color is from a light yellow to an orange, to a 
purplish-brown, and finally to a very dark 
purplish or orange-brown color. 
Oogenesis occurs a second time during the 
reproductive season in about 70% of the fe- 
males. The progression of ova development is 
simultaneous with the embryonic development 
of those zygotes attached to the pleopods. Very 
shortly after the hatching of the first brood has 
occurred, copulation probably takes place and a 
second brood is brought forth. Inasmuch as his- 
tological sections were not made of the ovaries, 
it was impossible to detect accurately the exact 
time of the onset of oogenesis. By our tech- 
nique it would appear that early October is the 
time when activity can first be recognized with 
any certainty. 
PERIODS OF COPULATION: Very few observa- 
tions of copulation were made for this species 
either in the laboratory or in the field. Perhaps 
the small size of the individual and its drab 
coloration would account for this in part. Those 
records obtained were gotten around March 20 
and April 15. Using H. nudus and its total re- 
productive cycle as a partial guide, it is sug- 
gested that copulation in H. oregonensis may 
begin as early as the first of February and prob- 
ably continues until about April 20. In any 
event, it would seem that copulation occurs just 
shortly before egg deposition. Whether or not 
a second period of copulation is required is not 
known. Dissections of the spermatheca of those 
animals bearing ova have not been completed. 
Thus, knowledge of whether or not sufficient 
sperm is stored is lacking. Probably a second 
period of copulation is required, as in the case 
of Pachygrapsus eras sipes (Hiatt, 1948:200). 
ACT OF COPULATION: The act of copulation 
of H. oregonensis is similar to that of H. nudus 
and P. crassipes although this species, being 
smaller, may need even less time. The position 
is typical of that of H. nudus, as the male rolls 
over on his back and positions the female with 
her ventral thoracic surface against his. The 
chelae of the male are folded over the carapace 
of the female, extending in a posterior-median 
direction, thus forming a V. The walking legs 
are also used to hold the female or to alter her 
position. Our observations show that the male 
generally lifts the female and rolls over, simul- 
taneously positioning her after he is resting on 
his carapace. Thus, a minor difference between 
this species and H. nudus may exist in that the 
latter often positions the female before rolling 
backwards. A somewhat imperfect view of the 
act showed that the male H. oregonensis lowers 
the abdomen of the female in the manner de- 
scribed for H. nudus. 
An interesting observation made in an ex- 
perimental tank may shed some light on the 
initiation of copulation and thus is given almost 
in full as it appears in our laboratory notes. A 
pair was found in copulation and records were 
taken of the activity. For 25 min the pair 
remained in copulation with only slight ab- 
dominal movements and an occasional leg move- 
ment observed. At the end of this period, the 
female broke away and rushed across the tank 
where a second male abruptly caught her, rolled 
over and began copulation. The first male broke 
up this pair by shaking the new male loose. 
At this time the female darted under a rock. 
The male in pursuit, unable to reach her with 
his thick chelae, backed under the rock and 
pulled the female out by means of his last 
walking legs. The male then held the female 
without copulating, for over 40 min, attempting 
to position her from time to time. At the end 
of the period the male successfully copulated 
with the female until she again broke away. A 
new male caught the female and, in a fluid 
movement, rolled over and began copulation. 
The original male returned and succeeded in 
freeing the female in order to copulate with her 
again before she finally escaped to the safety of 
a rock crevice. 
It is of interest, first of all, that at least three 
of the five males in the aquarium were ready to 
copulate with the female whenever she was free, 
while one was even successful in dislodging 
other males in order to copulate. Second, there 
were nine other females of this species in the 
same tank, most of which later produced a batch 
of eggs, thus proving maturity and fertility. 
