Micronesian Gastropods — Demond 
291 
Fig. 6. Rhinoclavis tenuisculpta (Reeve). Bikini Atoll, 
Marshall Islands (USNM 580526). 
although entirely white specimens have been 
found. Aperture white. 
Found living in sand on lagoon floors and 
off the edge of seaward reefs, at depths of 
10 to 500 feet. 
geographic range: USNM collections 
are distributed from Mauritius eastward 
throughout the Indian and Pacific oceans to 
Midway Island and the Tuamotus, and from 
southern Japan south to northern Australia. 
Fairly common in Micronesia, but apparently 
replaced in Hawaii by R. granifera Pease. 
Rhinoclavis vertagus (Linne, 1767). 
Hirase and Taki (1951) pi. 83, fig. 2. 
Characteristically 1.5 to 2.5 inches long. 
The recent Micronesian collections contain 
only one specimen, found living among inter- 
tidal rocks on the beach at Tomil Harbor, 
Yap. 
GEOGRAPHIC range: USNM records are 
distributed from Mauritius and Ceylon east- 
ward through the Indian and Pacific oceans 
only as far as the Caroline and Solomon is- 
lands, and from the Ryukyu Islands south to 
northern Australia. An uncommon species in 
Micronesia. Not found in Hawaii. 
Genus Cerithium Bruguiere, 1789 
Cerithium alveolus Hombron and Jacquinot, 
1841 (syn. C. piperitum Sowerby, 1855). 
Characteristically less than one-half inch 
long. Shell white, covered with spiral ridges 
of varying depth and with many fine, brown 
spots. Columella violet. C. alveolus super- 
ficially resembles C. sejunctum , but it is more 
slender, its brown markings are finer, its spiral 
ridges are not nodose, and its outer lip is not 
violet. 
The many specimens from the Marshall 
Islands in the collections studied indicate that 
C. alveolus is abundant on windward ocean 
reef flats where it lives in sandy depressions 
among rocks and in rocky tide pools. The 
collections also include several specimens from 
the sandy lagoon bottom of Tanapag Harbor, 
Saipan, found among small reefs at depths of 
10 to 15 feet. 
geographic range: USNM records are 
from the Mariana and Marshall islands only. 
Reported from the Ryukyu Islands and For- 
mosa, but not from Hawaii. Probably more 
widespread but rarely noticed because of its 
small size. Apparently fairly common in 
Micronesia. 
Fig. 7. Cerithium alveolus Hombron and Jacquinot. 
Bikini Atoll, Marshall Islands (USNM 583953). 
Cerithium columna Sowerby, 1855 (syn. echina- 
tum Kiener, 1841; not Lamarck, 1822). 
Tinker (1952) p. 166, 3 figs, on p. 167. 
Characteristically 0.75 to 1.5 inches long. 
Shell whitish. Aperture white. Spiral ridges 
between the nodes commonly dark brown. 
Ordinarily found buried in sand near and 
below low tide line. Most of the specimens 
in the recent Micronesian collections were 
