210 NATICIDA. 
which takes the salmon to the river, and the herring to shallower 
water, migrated inshore and sought its proper spawning ground. 
MARSENINA, Gray. (? Colobocephalus, M. Sars.) Shell opaque, 
with short spire; animal with mantle fissured down the back. 
L. depressa, Sutton (1xiii, 59). 
ONCHIDIOPSIS, Bergh. Shell entirely enclosed by the animal, 
thin, slipper-like, without spire, margin entire. Animal verru- 
cose, with a lanceolate foot. O. glacialis, M. Sars ([xiv, 72, 73,. 
Norway. 
CRYPTOCELLA, H. and A. Adams. Shell thin, pellucid, calca- 
reous; spire small, mouth very large; animal with depressed, 
subverrucose or smooth mantle. L. tentaculata, Mont. (Lxiii, 60). 
L. latens, Mull. (1xiii, 61). 
CORIOCELLA, Blainy. Shell spiral, calcareous, thin, subopaque, 
spire short, whorls rounded, the last large, aperture very large. 
Mantle of animal deeply fissured and bilobed in front, the surface 
depressed and covered with numerous hexagonal tubercles. 
This group was founded by Blainville upon an animal accidentally 
deprived of its shell. ZL. nigra, Blainv. (1xiii, 62, 63). 
V ANIKORO, Quoy and Gaimard. 
Syn.—Narica, Recluz. Merrya, Gray. lLeucotis, Sowb. 
Distr.—25 sp. West Indies, Nicobar, Philippines, Polynesia. 
Fossil. Gault —; Europe, U. 8S. V. cancellata, Chemn. 
(Ixv, 90). 
Shell subglobose, external, white, with sometimes a velvety 
epidermis, striated, costate or decussated, umbilicated, umbilicus 
without a trace of callus. Operculum very thin, corneous, not 
spiral. 
Probably most of the jurassic and triassic species of Neritopsis 
belong to Vanikoro, as certainly do nearly all the species 
described by Munster and Klipstein from St. Cassian under the 
name of Naticella. There are numerous cretaceous species from 
the old world. 
VANIKoropsis, Meek. Shell subglobose, thick and solid ; body- 
volution large; spire depressed; aperture ovate; axis imper- 
forate ; outer lip simple, beveled; inner lip closely folded upon, 
and adhering to, the columella and the body-volution , very little 
thickened and not flattened, toothed, aie or serrated ; surface 
with distinct revolving lines and furrows, and on the body- 
volution developing strong oblique folds or plications and 
furrows, parallel to the lines of growth. WN. Tuomeyana, M. and 
jal (Ixiv, 87). Cretaceous; Upper Missouri River. 
NATICODON, Ryckholt. Shell globose like Vanikoro, but the 
inner lip usually thickened and always provided with some kind 
of a tooth ; the columella is either slightly hollowed out or solid ; 
the surface smooth or ornamented with various spiral or trans- 
