294 NERITID. 
foot oblong, triangular. Lingual dentition similar to the Turbi- 
nide. Teeth 7; uncini very numerous (xii, 44, 45). 
Nerira, Linn. 
Ktym.—Nerites, a sea-snail, from Nereis. 
Distr.—Over 200 sp. Nearly all warm seas. West Indies, 
Red Sea, Zanzibar, Philippines, Australia, Central Pacific, West 
America. Many of the American species dwell in the streams ; 
one species at the Philippines sometimes climbs up trees. 
Fossil, 60 sp. Lias—; Britain, ete. The palwozoic Nerites 
are referred by d’Orbigny to Turbo, Natica, ete. 
N. polita, Linn. WN. peleronta, Linn. WN. histrio, Linn. N. 
undata, Linn. (1xxviii, 51-54). 
Shell thick, smooth or spirally grooved; epidermis horny ; 
outer lip thickened and sometimes denticulated within; colu- 
mella broad and flat, with its inner edge straight and toothed. 
Operculum shelly. 
Animal with the mantle-margin festooned. Living on rocks 
and stones, and said to be most active during the night, when 
they roam about, feeding on the alge; their eggs are ovate, 
covered with a horny skin, and attached to other shells. 
PELERONTA, Oken. (Pila, Klein. Ritena and Tenare, Gray.) 
Inner lip rugose, outer lip dentate within. N. Deshayesii, Recluz 
(Ixxviil, 55): 
THELIOSTYLA, Morch. (Natere, Gray. Dontostoma, Klein.) 
Inner lip granulated ortuberculated. N. exuvia, Linn. (1xxvili,56). 
DEIANIRA, Stolicz. Shell subglobose, consisting of few whorls, 
the last of which is the largest, often carinated posteriorly ; 
aperture large, semilunar; inner lip thick with three folds, the 
posterior one of which is the strongest. Operculum broadly 
oval, calcareous, with a tooth on the inner edge, and a groove 
corresponding to the strong posterior fold of the inner lip. Cret., 
fresh and brackish water deposits of the N. Eastern Alps. WN. 
bicartnata, Stol. (xxviii, 57, 58). 
LISSOCHILUS, Peth6., 1882. Outer lip sharp, not thickened nor 
dentate within, inner lip not dentate. Triassic and Jurassic. 
N. sigaretina, Buv. 
otostomMaA, d’Arch., 1859. (? Lyosoma, White.) Shell thick, 
globose ; upper part of body-whorl with somewhat curved folds 
and very fine spiral lines; inner lip callously thickened, toothed ; 
outer lip obliquely truncate, not thickened within. N. rugosa, 
Heeningh. Cretaceous. 

DeEsHAYESIA, Raulin, 1844. 
Etym,.—Dedicated to M. Deshayes, author of ‘“ Description des 
Animaux sans Vertébres dans le bassin de Paris,” ete. 
Syn.—Naticella, Grateloup (non Munster). Oneochilus, Petho., 
1882. 
