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PACIFIC SCIENCE, Vol IV, April, 1950 
Fig. 42. Peronia sp. a, Egg structure; b, magnified section of egg structure showing a double cap- 
sular enclosure for ova; c—g, cleavage stages; h, gastrula ?; i, early veliger with extremely large en do- 
dermal cells; j, free-swimming veliger; k, l, shell of free-swimming veliger. 
shell was brown. Eyes were present. The foot 
was large with a conspicuous operculum. 
The shell was about 0.33 mm. in length 
(Fig. Ale). The embryos all died, so the free- 
swimming stage was not observed. 
Family ON CH IDIIDA E 
Genus Peronia 
Peronia sp. 
Fig. 42 
Early in September, 1921, a number of 
specimens of Peronia were gathered from 
crevices in the sea wall near the laboratory. 
These were placed in a jar with running 
water, from which they soon escaped, being 
air-breathers, and scattered all over the aquar- 
ium tables. Some crawled into dark, wet cor- 
ners of wooden boxes, where they seemed to 
thrive. Some lived thus for months in the 
laboratory. It is obvious that this mollusk 
cannot live under water, while, on the other 
hand, it needs to be kept wet constantly with 
sea water. It has been found at Kaena Point 
and Black Point on the shore rocks above 
high tide level and where only the spray 
could reach it. A large number of these mol- 
lusks were found at Kawailoa, Oahu, during 
June. 
