Hawaiian Marine Gastropods — OsTERGAARD 
Family FIMBRUDAE 
Genus Melibe 
Melibe pilosa Pease 
Fig. 40 
Early in February, 1922, some egg struc- 
tures were deposited in the laboratory by 
specimens of Melibe pilosa found close to the 
laboratory pier. The egg structure consisted 
of a very thin, broad, white ribbon, greatly 
folded, and spirally wound several turns, 
united by the inner edges, by which it was 
attached to a rock or other object (Fig. 40a) . 
Transversely arranged within the capsular 
wall, and closely filling the space, was a cy- 
lindrical tube packed with egg cases arranged 
in a single row. These egg cases, or hyaline 
envelopes, had the shape of a hen’s egg and 
measured about 0.17 mm. by 0.25 mm. Each 
case contained one ovum which had an aver- 
age diameter of 0.125 mm. (Fig. 40£). 
Development of the embryo was not in- 
b, magnified section of ribbon showing ova in 
hyaline capsules contained in tubes; c, d, shell of 
free-swimming veliger. 
Ill 
vestigated, but a study of the veliger shell was 
made. This was elongate, pellucid and color- 
less, about 0.2 mm. in length (Fig. 40 c, d ) . 
0.1 mm. 
Fig. 41. Siphonaria normalis omara Reeve, a, 
Egg ribbon; b, magnified section of ribbon show- 
ing compact masses of hyaline capsules with ova; 
c, unhatched veliger stage. 
Order PULMONATA 
Family SIPHON ARUDAE 
Genus Siphonaria 
Siphonaria normalis omara Reeve 
Fig. 41 
On September 9, 1923, a specimen of 
Siphonaria deposited an egg structure in the 
laboratory, several of the animals having 
been brought in from the near-by sea wall. 
The egg structure was a somewhat thickened 
colorless ribbon, arranged in a half circle 
which measured about 3 cm. in length and 
2 mm. in width. The walls of the ribbon 
were very thick and fibrous, and the eggs were 
closely packed in two layers. A rather ovoid 
hyaline envelope surrounded each ovum. 
This envelope measured about 0.485 mm. in 
length and 0.34 mm. in width; the diameter 
of the ova was about 0.19 mm. (Fig. 41^, b ) . 
Steps in development were not observed, 
but a study of the embryo when it had reached 
the veliger stage was made. The color of the 
animal was pale greenish, while that of the 
