288 
GEOGRAPHIC range: USNM collections 
are from the entire east African coast, east- 
ward through the Indian and Pacific oceans 
to the Society, Tuamotu, and Marquesas is- 
lands, to Clipperton Island in the eastern 
Pacific, and from southern Japan and Hawaii 
south to Queensland, Australia. N. plicata is 
very common throughout the Indo-Pacific. 
Nerita polita Linne, 1758. 
Hirase and Taki (1951) pi. 75, fig. 13; 
Morris (1952) p. 165, pi. 36, fig. 16; 
Kira (1955) pi. 11, fig. 19. 
Characteristically about one and one-half 
inches long, with a smooth, polished shell 
mottled with grey, white, and black. 
N. polita lives among rocks at and above, 
but generally not below, high tide line along 
both ocean and lagoon shores. During the day 
it remains buried about an inch deep in sand 
between the rocks. At night it browses on the 
algae-covered rock surfaces. 
geographic range: USNM collections 
are from the entire east African coast, includ- 
ing the Red Sea, 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, New Guinea, 
and New Caledonia. Reported from northern 
Australia. Very common throughout the 
Indo-Pacific. 
Nerita signata Lamarck, 1822 (syn. reticulata 
Karsten, 1789, nonbinom.). 
Characteristically 1 to 1.25 inches long, 
with raised spiral ribs crossed by numerous 
fine, wavy crenulations. 
The recent Micronesian collections contain 
only one individual, found among intertidal 
rocks of the beach at Tomil Harbor, Yap. 
geographic range: Apparently limited to 
the Pacific, uncommon in Micronesia, and 
absent from Hawaii. USNM records are from 
the Ryukyu Islands, Gulf of Siam, Borneo, 
and the Philippine, Caroline, Fiji, and Gilbert 
islands. 
PACIFIC SCIENCE, Vol. XI, July, 1957 
Fig. 3. Nerita signata Lamarck. Yap Island, western 
Carolines (USNM 614206). 
Nerita undata Linne, 1758. 
Characteristically 1 to 1.5 inches long, 
blackish with a white columella and aperture, 
and bearing numerous spiral incised grooves. 
Specimens in the collections studied were 
found on and under rocks at or near high 
tide line along the tidal flats and rocky beach 
Fig. 4. Nerita undata Linne. Yap Island, western 
Carolines (USNM 614207). 
