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PACIFIC SCIENCE, Vol. XI, July, 1937 
pale rust-colored pustules and ridges covering 
a grayish dorsum, a distinct median dorsal 
furrow, extremities produced and beaked, and 
teeth extending over the base onto the 
margins. 
Apparently lives below low tide line on 
both seaward and lagoon reef flats. The one 
specimen in the present Micronesian collec- 
tions which was taken alive came from among 
small reefs on the sandy lagoon shelf at Ifaluk. 
These reefs are never exposed, their surfaces 
ordinarily being covered by 3 to 5 feet of 
water at low tide. 
GEOGRAPHIC RANGE: USNM collections are 
from East Africa and Mauritius eastward 
throughout the Indian and Pacific oceans to 
the Society, Tuamotu, and Line islands, and 
from southern Japan south to New Guinea 
and New Caledonia. Reported from northern 
Australia and Hawaii. Uncommon in Mi- 
cronesia. 
Family CASSIDIDAE— Helmet Shells 
Genus Cassis Scopoli, 1777 
Cassis cornuta (Linne, 1758). 
Hirase and Taki (1951) pi. 97, fig. 1; Tinker 
(1952) p. 128, fig. on p. 129; Morris 
(1952) p. 183, pi. 38, fig. 14. 
The largest species of Cassis , commonly 10 
to 14 inches long. Whitish with 7 or 8 dark 
brown rays on the outer lip. Aperture flesh- 
colored and polished. 
Ordinarily lives in sand among small reefs, 
on lagoon slopes at depths of 5 to 20 feet. 
According to USNM collection notes by 
John Wells, the Arno natives claim that C. 
cornuta comes up from the lagoon bottom 
onto the lagoon reef flat during new moon. 
Perhaps corroborating this behavior is the 
fact that two of the present Ifaluk specimens 
were collected during new moon along the 
shallow shore of the lagoon. 
GEOGRAPHIC range: USNM collections are 
from East Africa eastward through the Indian 
and Pacific oceans to Samoa, and from the 
Ryukyu and Marshall islands south to the 
Caroline Islands. Reported from southern 
Japan, Hawaii, and northeastern Australia. 
Fairly common in Micronesia. 
Genus Phalium Link, 1807 
Subgenus Casmaria H. and A. Adams, 1853 
Phalium ( Casmaria ) vibex (Linne, 1758). 
Tinker (1952) p. 130, 3 figs, on p. 131; 
Morris (1952) p. 183, pi. 38, fig. 13. 
Characteristically about two inches long, 
whitish or brownish with dark brown rays on 
the outer lip and a polished white aperture. 
Apparently lives on seaward reef flats in 
shallow water below low tide line. The one 
specimen in the recent Micronesian collec- 
tions which was taken alive was found among 
rocks in about 3 feet of water on the seaward 
reef flat at Ifaluk. Edmondson (1946) reports 
that, although P. vibex is a common Hawaiian 
species, it is seldom taken alive on the reefs. 
This comment indicates that the species lives 
in deeper water off the reef front. 
geographic range: Fairly common 
throughout the Indo-Pacific. USNM collec- 
tions are from East Africa and Mauritius east- 
ward throughout the Indian and Pacific oceans 
to Hawaii and the Tuamotu Islands, and from 
the Ryukyu Islands south to northern Aus- 
tralia and New Caledonia. 
Family CYMATIIDAE -Triton Shells 
Genus Cymatium Roding, 1798 
Subgenus Lampusia Schumacher, 1817 
Cymatium (Lampusia) chlorostomum (Lamarck, 
1822). 
Tinker (1952) p. 126, 2 figs, on p. 127; 
Morris (1952) p. 184, col. pi. 6, fig. 10. 
Characteristically 1.75 to 4 inches long and 
solid, with strong varices, prominent columel- 
lar plications, and apertural teeth. Shell whit- 
ish with brownish spots and a bright orange 
aperture and columella. 
Ordinarily lives among rocks and in tide 
pools on windward ocean reef flats, com- 
