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PACIFIC SCIENCE, Vol. XI, July, 1957 
ward through the Indian and Pacific oceans 
to the Marshall, Gilbert, and Samoan islands, 
and from southern Japan, the Ryukyu and 
Mariana islands south to New Guinea and 
New Caledonia. Reported from northern Aus- 
tralia, but not found in Hawaii. Fairly com- 
mon in Micronesia. 
Genus Drupa Roding, 1798 
Drupa grossularia Roding, 1798 (syn. digitata 
Lamarck, 1816). 
Tinker (1952) p. 96, 3 figs, on p. 97 [as 
D. digitata Lamarck]; Morris (1952) p. 
187, pi. 39, fig. 3, col. pi. 8, fig. 5 [as 
Sistrum digitatum Lamarck]; Kira (1955) 
pk 23, fig. 3. 
Characteristically 1 to 1.5 inches long, with 
an orange aperture and, in adult specimens, 
with fingerlike protuberances on the outer 
lip. This Drupa is commonly so encrusted 
with coralline algae, vermetids, Foraminifera, 
and other growth, that its shape is entirely 
obscured and it appears to be part of its 
substrate. 
Ordinarily found on windward ocean reef 
flats, clinging to the rocks near low tide line. 
Less frequently occurs on leeward ocean reefs. 
Only one specimen in the recent Micronesian 
collections was from a lagoon habitat. It was 
taken alive from coral-algal rock at a depth 
of 32 to 38 feet in the lagoon entrance west 
of Saipan. 
GEOGRAPHIC range: Apparently limited to 
the Pacific, and fairly common in Micronesia. 
USNM collections are from Formosa and the 
Philippines eastward to the Hawaiian, Society, 
and Tuamotu islands, and from the Ryukyus 
south to New Guinea and Fiji. Reported from 
northern Australia. In the Indian Ocean, D. 
grossularia is replaced by the subspecies D. 
lobata which is recognized by its dark brown 
aperture. 
Drupa morum Roding, 1798 (syn. horrida 
Lamarck, 1816; violacea Schumacher, 1817; 
neritoides Gmelin, 1791, not Linne, 1758). 
Hirase and Taki (1951) pi. 110, fig. 8; 
Tinker (1952) p. 94, 3 figs, on p. 95 [as 
D. horrida Lamarck]; Kira (1955) pi. 23, 
fig. 8. 
Characteristically about one and three- 
fourths inches long. 
D. morum lives among rocks and in crannies 
of windward ocean reef flats. It is also com- 
mon on windward lagoon reef flats of broad 
atolls, such as Bikini and Eniwetok, where 
the surf is strong, but it seldom occurs on 
leeward reefs. Ordinarily, it is found near low 
tide line, or on the reef edge, but it has also 
been taken from tide pools across the entire 
reef flat. Specimens are commonly so over- 
grown with coralline algae, vermetids, Fora- 
minifera, and Hipponix they are almost indis- 
tinguishable from the reef surface. 
geographic range: USNM collections are 
from Mauritius eastward through the Indian 
and Pacific oceans to the Society and Tua- 
motu islands, and from southern Japan and 
Hawaii south to the East Indies and New 
Caledonia. Common in Micronesia. Reported 
from northern Australia and also from Clip- 
perton Island in the eastern Pacific (Hertlein 
and Emerson, 1953). 
Drupa ricinus (Linne, 1758) (syn. hystrix 
Linne, 1758, not Lamarck, 1822; arachnoides 
Lamarck, 1816). 
Hirase and Taki (1951) pi. 110, fig. 11; 
Tinker (1952) p. 96, 3 figs, on p. 97. 
Characteristically 0.75 to 1 inch long, and 
ordinarily encrusted with coralline algae, ver- 
metids and other growths. 
Habitat similar to D. morum . 
geographic range: USNM collections are 
from Mauritius eastward through the Indian 
and Pacific oceans to the Marquesas Islands, 
and from southern Japan and Hawaii south 
to the Great Barrier Reef, Australia, and New 
Caledonia. Very common in Micronesia. 
Hertlein and Emerson (1953) report D. ricinus 
from Clipperton Island in the eastern Pacific. 
Drupa rubusidaeus Roding, 1798 (syn. hystrix 
Lamarck, 1822). 
Hirase and Taki (1951) pi. 110, fig. 10. 
