Micronesian Gastropods — Demond 
293 
Fig. 9. Cerithium salebrosum Sowerby. Ifaluk Atoll, 
Caroline Islands (USNM 614197). 
GEOGRAPHIC range: USNM records are 
exclusively from atolls in the Caroline, Mar- 
shall, and Gilbert islands. Appears to be un- 
common in Micronesia, and absent from 
Hawaii, but is probably more widespread than 
the records indicate, being rarely noted be- 
cause of its small size and relatively deep water 
habitat. 
Cerithium sejunctum Iredale, 1929 (syn. varie- 
gatum Quoy and Gaimard, 1834, preocc.). 
Fig. 10. Cerithium sejunctum Iredale. Bikini Atoll, 
Marshall Islands (USNM 580070). 
Characteristically about one-half inch or 
less in length and with granose spiral ridges. 
Shell whitish, mottled with varying shades of 
brown. Aperture typically pale violet, partic- 
ularly on the columella and outer lip. Or- 
dinarily found buried in sand near or a few 
feet below low tide line. Most of the speci- 
mens in the recent Micronesian collections 
were living in sand among rocks and in rocky 
tide pools on windward ocean reef flats. Ab- 
bott (1950) reports C. sejunctum to be "plenti- 
ful in the lagoon in shallow, weedy water" at 
Cocos-Keeling Atoll. 
GEOGRAPHIC range: USNM records are 
from Cocos-Keeling Atoll in the Indian 
Ocean and from the Marshall, Gilbert, Phoe- 
nix, and Fiji islands in the Pacific. Reported 
from southern Japan and Formosa, but not 
from Hawaii. Common in Micronesia. 
Cerithium tuherculiferum Pease, 1869. 
Tinker (1952) p. 166, 2 figs, on p. 167 
[as C. echinatum Lamarck]. 
Characteristically 1.5 to 2.25 inches long 
and sculptured with spiral, tuberculated cords 
which are spinose around the periphery of 
each whorl. Shell whitish with irregular brown 
markings. Aperture white. 
Found buried in sand among rocks and 
coral patches below low tide line on seaward 
and lagoon reef flats and at depths of a few 
feet in channels between reefs. 
geographic range: USNM records are 
from the Philippine, Mariana, Marshall, Gil- 
bert, Loyalty, Samoan, Society, Tuamotu, 
Phoenix, Line, and Hawaiian islands. Not 
reported from southern Japan or Australia, 
but fairly common in Micronesia. 
Family HIPPONICIDAE-Hoof Shells 
Genus Hipponix Defrance, 1819 
Subgenus Sabia Gray, 1847 
Hipponix (Sabia) conicus (Schumacher, 1817). 
Characteristically 0.25 to 0.75 inch long, 
with irregular radial ribs, and white with a 
dark brown muscle scar inside the shell. Com- 
monly lives below low tide line on seaward 
reef flats, attached to the shells of other gas- 
tropods, typically around the aperture. A spe- 
cies with similar attachment habits (H. austra- 
lis) has been observed by Risbec (Yonge, 
1953) to feed upon the fecal pellets of the 
host. Specimens in the present collections 
were found on Turbo setosus , etc. Morrison 
and Cloud report a possibly unrecorded spe- 
cies of Hipponix which they found in Micro- 
nesia attached to corals, algae, or rocks; they 
believe it feeds on detritus, as does the com- 
mon California H. antiquatus (Yonge, 1953). 
Specimens in the present collections were 
found on Turbo setosus and T. argyrostomus, 
Vasum turbinellue and V. ceramkum , Thais ar- 
