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PACIFIC SCIENCE, Vol. IV, April, 1950 
the shore during the cooler months of the 
year, at which time its filaments were also 
found in abundance. As in the preceding 
species the fresh filament was white or pale 
yellow and, as development of the young 
progressed, it turned to a yellowish-brown. 
The structure of the filament and the type 
of cleavage agreed in nature with those of 
T. grandis. However, a note on the veliger 
shell is of interest. The shell measured about 
0.125 mm. in length and consisted of about 
one volution, was a light golden-brown in 
color, darkest along the columellar line. The 
operculum was large and round as in T. 
grandis. Otoliths appeared distinctly within 
the otocysts (Fig. 22c, d, e) . 
Fig. 23. Tethys (= Aplysia) elongata (Pease). 
a, Egg filament; b, magnified section of filament 
with early cleavage stage; c, d, free-swimming 
veliger larva; e, shell with operculum of free- 
swimming veliger. 
Tethys (— Aplysia) elongata (Pease) 
Fig. 23 
Early in March, 1923, a specimen of Tethys 
elongata found near the Elk’s Club, Waikiki, 
was brought to the laboratory. This animal 
was in general of a much darker color than 
the species but otherwise seemed to agree and 
might be considered a color variety. Two 
months later five more specimens like it were 
found in the same location. 
An egg filament was deposited by this 
mollusk in the laboratory. This was a pale 
green, tangled, cylindrical filament of about 
0.5 mm. in diameter. The lumen of the fila- 
ment was closely packed with globular hy- 
aline capsules with an average diameter of 
0.125 mm., lying about four abreast in a 
cross section and each containing one ovum. 
The first cleavage of the zygote was usually 
equal, while the second was unequal, result- 
ing in two micromeres and two macromeres. 
The micromeres soon divided, giving the em- 
bryo its triangular appearance, corresponding, 
perhaps, to the morula stage (Fig. 23 a, b). 
The free-swimming veliger stage was 
reached in 11 days, and the larva then, quite 
colorless, was provided with otocysts but with 
no eyes. The shell, which was about 0.125 
mm. in length, had a golden tinge and a red- 
dish columellar region. A well-developed 
operculum was present (Fig. 23 c, d, e). 
Genus Dolabrifera 
Dolabrifera olivacea Pease 
Fig. 24 
For a long time I sought in vain for 
the spawn of this mollusk, so common un- 
der loose, flat, shore rocks. Finally on Febru- 
ary 18, 1922, an animal that was kept in a 
glass jar laid a peculiar, flat egg ribbon. 
Later in the season — on May 25 — I found, 
on the underside of a number of concrete 
slabs to which the mollusks were clinging, 
many of their ribbons. This egg structure is 
easily overlooked as it is clear and colorless — 
a flat band with the flat side attached to the 
smooth surface of a rock or other object, and 
spread out so as to cover a surface of 5 or 
more square centimeters. The ribbon rarely 
overlapped, but was often spread out so neatly 
that it formed a series of slightly curved 
parallel rows (Fig. 24^ b) . 
I happened to observe one of the mollusks 
in the act of laying eggs. The ribbon passed 
anteriorly, from the genital pore in the dorsal 
