264 RISSOIDA. 
mella very broad, expanded, and continuous with the peristome. 
P. tuba, Desh. (Ixxii, 42). Eocene; Grignon, Paris. 
seTIA, H. and A. Adams. Shell thin, oval-oblong or subconic ; 
whorls few, ventricose, spotted ; spire short, apex obtuse; aper- 
ture suborbicular. Animal with pilose tentacles. &. pulcher- 
rima, Jeffreys (1xxii, 43). 
cCERATIA, H. and A. Adams. Shell subcylindrical, spirally 
striated, white, thin, subpellucid; whorls rounded, summit of 
spire obtuse; aperture suboval; peristome continuous, the outer 
lip thin and sharp. Animal with flattened, mostly short and 
claviform tentacles ; foot bifurcate behind. &. proxima, Alder 
(Ixxii, 44). 
cincuLA, Fleming. Shell thin, elongated, smooth or spirally 
striate, spotted or banded; aperture pyriform or oval; outer lip 
sharp, with an external varix. &. cingillus, Montf. (xxii, 45). 
onoBA, H. and A. Adams. Shellelongated ; whorls numerous, 
rounded, spirally striate; aperture oval; peristome continuous, 
thick, simple or slightly reflected. R. striata, Mont. (1xxii, 46). 
ALVANIA, Risso. Shell oval, turbiniform; spire short, apex 
sharp; whorls rounded, usually cancellated; aperture subcir- 
cular, crenulated within; outer lip with a marginal exterior 
varix. &. abyssicola, Forbes (1xxii, 47). 
SABAN/ZA (Leach), Frauenfeld. Shell thick, stout, smooth. 
Australia, Europe. &. flammea, Frauenf. (1xxii, 48). 
cORENA, A. Ad. Shell elately turbinate, rimate, apex obtuse ; 
aperture circular, with continuous peritreme; inner lip with a 
thin callous expansion, and acute posterior tubercle; outer lip 
with duplicated margin, well-reflected. Dist7.—1 sp. Gulf of 
Suez. 
HEMISTOMIA, Crosse. Shell subimperforated, elongated, thin ; 
spire long, summit obtuse, suture well-marked ; aperture ob- 
liquely semilunar; peristome simple, continuous, almost de- 
tached; columellar margin very oblique, thickened; basal 
margin widely rounded. Operculum unknown. New Cale- 
donia. R&R. Caledonica, Crosse (1xxii, 49). 
AMPHITHALAMUS, Carpenter, 1865. Shell rissoid, with a large 
nucleus; inner lip produced, outer lip joining it subposteriorly, 
suddenly contracted in the adult. Several minute species. 
California, Japan. &. inclusa, Carp. 
FENELLA, A. Ad., 1860. Has the pupoid form of Rissoa, with 
longitudinal and transverse ribs; the outer lip without a varix. 
May perhaps belong to Pyramidellidz, with which the animal 
nearly corresponds. &. pupoides, A. Ad. Japan. 
DIASTOMA, Desh., 1848. Shell turreted, whorls with numerous 
transverse ribs, and with a few intermediate varices. Inner 
margin of the aperture partially detached from the previous 
whorl; the aperture itself is strongly contracted posteriorly. 
