CERITHIID A. 949 
Mesostoma, Deshayes, 1864. 
Distr.—Fossil, 4 sp. Eocene; Paris. MJ. grata, Dh. 
Shell elongated, turreted, scalariform ; aperture nearly circu- 
lar, dilated, obliquely cut, terminating in front by a semicanal- 
iculated angle ; columella slightly concave, cylindrical, obliquely 
truncated, lip simple, and slightly expanded. 
ExeE.issa, Piette, 1861. 
Etym.—E zelisso, to unfold. Syn.—Kilvertia, Lycett, 1863. 
Distr.— Fossil, 14 sp. Mid. Lias to Kimmeridge Clay ; 
England and France. Cretaceous, 1 sp. (?); India. H. formosa, 
Lycett (Ixix, 62). 
Shell small, elongated subcylindrical, somewhat pupiform, 
many-whorled, perpendicularly costated, tuberculated or spined ; 
last whorl cylindrical, contracted at the base, with a tendency 
to separate from the axis; aperture orbicular, entire, the lips 
elevated, produced, and slightly thickened ; columella solid. 
Includes a large number of very characteristic transversely 
ribbed species. It is uncertain whether there was an anterior 
canal or not, and therefore the pertinence of the genus to this 
family remains doubtful. . 
FASTIGIELLA, Reeve. 
Distr.—l recent sp.; and an Eocene sp., Paris basin. F. 
carinata, Reeve (1xx, 64). 
Shell elongated, turriculated, whorls rounded, with revolving 
ribs; aperture prolonged into a short, slightly twisted canal; 
axis rimate. 
Trirorts, Deshayes. 
Syn.—Tristoma, Blainy. 
Distr.—100 sp. E. Indies, Polynesia, Australia, Panama, W. 
Indies, Mediterranean. Fossil. Eocene; Europe. T. perversus, 
Linn. (xix, 58). 
Shell sinistral, sculptured, granular; whorls numerous, termi- 
nating below in a small aperture, with tubular anterior canal; 
opposite this canal is sometimes a second one upon a varix, 
marking the position of a former aperture. Operculum orbicu- 
lar, few-whorled. 
Animal. Tentacles clavate at the tips, united at their bases 
by a sinuated veil. 
tno, Hinds. (Inella, Bayle.) Shell cylindrically subulate, 
elongated, spire sharp-pointed. 7. corrugatus, Hinds (lxix, 59). 
sycHAR, Hinds. Shell elongated, whorls rounded. 7’ vitreus, 
Hinds (xix, 60). 
MASTONIA, Hinds. Shell acuminated, swollen in the middle. 
T. vulpinus, Hinds (1xix, 61). 
L&ococuiis, Dunker and Metzger... Shell turreted; whorls 
aly 
