AURICULIDA. 93 
the sea; mostly tropical in distribution, at least as to the larger 
species. 
The inner walls of the whorls are usually absorbed, so as to 
form a single cavity for most of the interior (i, 14). 
AuvricuLa, Lam., 1799. 
Ktym.— Auricula, a little ear. 
Syn.—Hllobium, Bolten? 1798. Marsyas, Oken, 1815. Ge- 
ovula, Swains., 1840. Auriculus, Montf., 1810. 
Distr.—44 sp. East Indies, New Caledonia, South America, 
Philippines, Australia. A. Wid, Linn. (cii, 70). 
Shell oblong-oval, covered by a thin epidermis; spire short, 
conoidal, very rarely subelongated ; last whorl large; rounded 
at the base; aperture longitudinal, narrow, ear-shaped; inner 
wall of the aperture with two or three plications; peristome 
thickened internally, without teeth. 
A. Jude, Linn., has truncated tentacles. The species are 
mostly found in brackish-water swamps, in tropical islands, and 
several of them are known to be blind. 
sionA, H. and A. Adams, 1858. (Sarnia, H. and A. Adams, 
1855.) Shell oval-cylindrical; spire obtuse; whorls transversely 
striate ; aperture linear; inner lip plicate; outer lip thickened 
within, sinuous behind. A. avena, Petit. 
PYTHIOPSIS, Sandberger, 1870. Shell oval-conie, with a line of 
varices, sometimes on one side, sometimes on both sides; coln- 
mellar wall with two plications, the posterior small, the anterior 
subhorizontal; base of the columella plicate and twisted; lip 
thickened within but not dentate. A.ovata, Lam. Eocene. This 
group connects Auricula with Scarabus. 
AURICULASTRA, Martens. Aperture with thickened lip; shell 
small, with elevated spire. A. subula, Quoy. 
CassIDULA, Fer., 1819. 
Sy».—Sidula, Gray, 1840. Rhodostoma, Swn., 1840. 
Distr.—27 sp. Ceylon, East Indies, Philippines, Australasia, 
Polynesia. Fossil; C.wmbilicata, Desh. Miocene of Touraine. 
C. angulifera, Petit (cii, 71). 
Shell subperforated, cassidiform, solid; spire short, conoidal; . 
last whorl very large, attenuated to the base, where it is usually 
carinated or angulated around the axis; aperture narrow, sin- 
uous ; inner lip dentately plicate ; columellar plication strong ; 
outer lip thickened within by a strong callosity with toothed 
edge. 
Foot bifid behind; tentacles slim and pointed, with eyes 
slightly raised at their internal base. 
Usually inhabits mangrove-swamps, and among loose stones 
near the sea-shore; some species are amphibious, and at high 
