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PACIFIC SCIENCE, Vol. XI, July, 1957 
the Indian and Pacific oceans to Palmyra 
Atoll and the Tuamotu Islands, and from 
southern Japan south to New Guinea, Fiji, 
and Tonga. Fairly common in Micronesia, 
but not reported from Australia or Hawaii. 
Thais tuherosa Roding, 1798 (syn. pica Blain- 
ville, 1832). 
Characteristically 1.5 to 2.25 inches long. 
Triangular in shape and covered with broad, 
pointed knobs. Aperture typically yellowish- 
white with a few large, dark brown spots on 
both the outer lip and columella. 
The recent Micronesian collections include 
only two specimens, both from the windward 
shore of Saipan. They were found living in 
shallow water on rocky intertidal reef flats. 
geographic range: Apparently limited to 
the Pacific. USNM records are from the Phil- 
ippines eastward through Micronesia to the 
Society and Tuamotu islands, and from south- 
ern Japan and the Ryukyu Islands south to 
northern Australia. Apparently uncommon in 
Micronesia. Not reported from Hawaii. 
Fig. 23. Thais tuherosa Roding. Samoa (USNM 
305758). 
Genus Purpura Bruguiere, 1789 
Purpura persicum (Linne, 1758). 
Characteristically 2 to 3.5 inches long. Ex- 
terior brownish with spiral lines of alternating 
brown and white elongate spots. Aperture 
orange or flesh-colored. 
Fig. 24. Purpura persicum (Linne). Ifaluk Atoll, 
Caroline Islands (USNM 614202). 
A single specimen was found living on the 
windward shore of Ifaluk, clinging to the 
rocky edge of the seaward reef flat, exposed 
to the breaking surf. 
geographic range: USNM records are 
from Mauritius, Ceylon, Cocos-Keeling 
Atoll, the East Indies, and the Philippine, 
Ryukyu, Bonin, Mariana, Caroline, Gilbert, 
and Loyalty islands. Reported from northern 
Australia but not from Japan or Hawaii. Un- 
common in Micronesia. 
Genus Nassa Roding, 1798 
Nassa sertum (Bruguiere, 1789). 
Hirase and Taki (1951) pi. HO, fig. 7 
[as Nassa francolinus Bruguiere]; Tinker 
(1952) p. 88, 5 figs, on p. 89; Morris 
(1952) p. 191, pk 39, fig. 12. 
Characteristically 1.5 to 2 inches long. 
Ordinarily ives among rocks near or 
slightly below low tide line on both seaward 
and lagoon reef flats, commonly just shore- 
ward of the reef edge. One specimen, from 
Ifaluk, was found on a small lagoon reef in 
3 to 5 feet of water. 
