Land Snails of Ulithi Atoll — Harry 
219 
Family DIPLOMMATINIDAE 
Palaina ovatula Mollendorff 
Palaina ovatula Mollendorff 1897, Nachr. d.d. 
Malak. Ges. 29:42. Not figured. Type locality: 
Ponape, Caroline Islands. 
Dr. Cooke identified this merely to genus, but 
noted that the same species occurs on Fais. 
The Bryant Walker Collection at the University 
of Michigan contains specimens from Ponape 
which agree closely with the shells from Mog- 
mog, except that they are slightly more ovate. 
The 38 shells from Mogmog examined are 
rather uniform in size, form and sculpture. All 
were slightly weathered, being light grey or dull 
white, and semiopaque by transmitted light. 
None contained the operculum or animal. 
Shell (Fig. 9) sinistral, ovate-cylindrical, 
rimate-umbilicate, with 3 44 suture whorls. The 
apex is obtuse, depressed. The whorls are evenly 
rounded, though somewhat distorted, the later 
whorls of the spire being slightly flattened. The 
plane thus produced coincides with the apertural 
plane. The aperture is subcircular, strongly bi- 
labiate by a heavy, multilamellate costa just be- 
fore the slightly reflected outer lip. The parietal 
lip is entirely adnate to the body whorl, and 
encroaches slightly on it. The latter character is 
somewhat variable. The aperture has no teeth 
or lamellae. The initial Wa whorls are smooth 
but not polished, beyond which gradually ap- 
pear minute, lamelliform costae, closely spaced. 
These gradually increase in size for about 1 
whorl, after which they maintain uniform size 
and spacing until the last half of the body 
whorl, where they become larger and less closely 
spaced. 
Family truncatellidae 
Truncatella ( Taheitia ) mariannarum Quadras 
and Mollendorff 
Dr. Cooke considered the Mogmog specimens 
very similar if not identical to specimens from 
Guam, which is the type locality. It also occurs 
on Fais. Clench and Turner (1948) have re- 
cently given a review of this group, but did not 
describe or figure this species, which seems not 
to have been previously figured. 
Adult specimens from Mogmog (Figs. 10, 
11, and 12) are about uniform in size, of 9 mm 
altitude, decollate, and of about 3 Va (suture) 
whorls. The fine costae number about 40, or 
slightly less, to the body whorl. On the body 
whorl there is a moderately vague, linear con- 
striction paralleling the suture a short distance 
below it. Above this constricting line the costae 
have a more distinct bladelike aspect than be- 
low. The constriction is less prominent on the 
last fourth of the body whorl and on the whorls 
of the spire. The base is imperforate, with a 
basal ridge moderately developed on the last 
half of the body whorl. Aperture symmetrically 
ovoid, scarcely expanded, unilabiate, the costae 
in even size-series before the lip, with none en- 
larged. Parietal lip moderately thickened, but 
entirely adnate to the body whorl. The costae 
do not extend over the basal ridge. 
Apex of 1 Va whorls, minutely and uniformly 
costate transversely, with an abrupt transition 
to the grosser costae of the later shell. Costae 
of early predecollate shell more acute than those 
of postdecollate whorls. The color is uniform 
chestnut brown. 
