STOMATELLID®. 317 
Shell ear-shaped, regular; spire small; aperture oblong, very 
large and oblique, nacreous; lip thin, even-edged. Operculum 
circular, horny, multispiral. On reefs and under stones at low- 
water. : 
StromatiA, Helbing. 
Etym.—Stoma, the aperture. 
Distr.—12 sp. Java, Philippines, Torres Straits, Pacific. 
Under stones at low-water.—Cumina. Fossil: M. d’Orbigny 
refers to this genus 18 species, ranging from the L. Silurian to 
the chalk. North America, Europe. 
Shell like Haliotis, but without perforations, their place being 
occupied bya simple furrow; surface rugose, spirally ridged ; spire 
small, prominent ; aperture large, oblong, outer margin irregular. 
Animal spiral, too large entirely to enter the shell; frontal 
lobes digitated, foot large, tubercular, greatly produced behind, 
lateral membrane fringed, ending anteriorly on the left side in a 
fimbriated crest under the eye-pedicel, and on the right in a 
slightly projecting fold or gutter leading to the respiratory 
cavity. Operculum, none. 
Stomatia, like Harpa and some nudibranchs, has the power 
of spontaneously throwing off the hind-part of the foot when 
the animal is irritated, and Gena exhibits the same peculiarity ; 
specimens in spirits have the foot usually truncated from this 
cause. Most numerous at the Philippines, on coral reefs, but 
also found under stones at low-water. 
MicroTiNna, H. and A. Adams. (Microtis, A. Ad.) Shell sub- 
orbicular, depressed, spire but slightly developed; whorls with 
two small tuberculated ribs; columellar lip twisted; aperture 
transversely oval. No operculum. Animal as in Stomatia, but 
the foot with a deep anterior fissure for the head, and with the 
front edge bilobed. 2sp. Philippines, New Caledonia. _ S. tuber- 
culata, Ads. (1xxxi, 75). 
NIPHONIA, Adams. Shell like Stomatella, but very thin; colu- 
mellar lip internally thickened, and gradually passing into the 
outer lip. S. pulchella, A. Ad. Japan. 
GENA, Gray. Shell subspiral, oblong, auriform, depressed, 
smooth or striated; spire flattened, nearly obsolete; aperture 
very large. No operculum. Animal with the front lobes 
plumose; foot very large, tubercular, posteriorly produced ; 
lateral membrane not fringed, more or less extended, and par- 
tially covering the shell. 16 sp. Red Sea, Indian Ocean, Phil- 
ippines, Australia. S. striatula, Ads. (1xxxi, 76). 
Puaneta, H. Adams. 
Distr.—P. Everetti, H. Adams (Ixxxi, 77,78). Siniwan River, 
Borneo ; attached to submerged logs. 
Shell imperforate, trochiform ; few-whorled, the last carinated, 
