116 
Psyche 
[September 
in g with the time when the water temperature had reached 
its maximum of 26.5 degrees C. In June 38.1 per cent of 
the number of clams with mites or papillae for that month 
contained masses of living mite eggs. The eggs at this 
time were all white or light yellow, indicating that they 
had been laid recently. Observations of Humes and Jamn- 
back (1950) have indicated that the eggs when first laid 
are light cream in color, but darken as development pro- 
gresses to almost black at hatching, which may occur in 
17 days in distilled water at summer room temperatures. 
In July many of the egg masses were various shades of 
brown, and some had already hatched. In August only 20.8 
per cent of the clams with mites or papillae contained egg 
masses. These were generally dark in color or already 
hatched. A few, however, were light cream in color, indi- 
cating recent oviposition. 
Dead egg masses were found in all months except 
January, February, and March (Graph 5). The absence 
of dead egg masses in these three months may be accounted 
for by the relatively small size of the samples of clams 
collected. Dead egg masses were never found in more than 
10.4 per cent (in August) of the clams with mites or 
papillae. Apparently egg masses which were laid late in 
the period of oviposition and had not hatched by the mid- 
dle of September died and remained in the suprabranchial 
chambers for several months. The dead egg masses found 
in April and May must have been laid during the preceding 
summer, since oviposition did not begin until sometime 
after the middle of May. 
No egg masses were found in E. complanatus or in L. 
radiata. 
Dead N. ingens (Graph 6) were found in parasitized A. 
cataracta in every month except March, a month when the 
small clam sample could account for their absence. Dead 
males occurred in small numbers during 6 of the 13 months, 
with no significant seasonal variation. Dead females oc- 
curred in every month except March, but were most abun- 
dant in July and succeeding few months. The sudden in- 
crease in incidence of dead females in July to 20.3 per cent 
of the parasitized A. cataracta occurred one month after 
