244 MANUAL OF THE MOLLUSCA. 
Cerith. radulum and granulatum of the West African rivers 
approach very near the fossil potamides, but they have numerous 
varices. 
Lampania, Gray (batillaria, Cantor). Cerith. zonale. Pl. 
Nae. Wis. 23, 
Shell without varices, canal straight. Chusan. 
The fossil potamides decussatus, Brug., of the Paris basin, 
resembles this section, and retains its spiral red bands. 
NERINZzA, Defrance. 
Etymology, nereis, a sea-nymph. 
Example, N. trachea. Fig. 98. 
Shell elongated; many-whorled, nearly cylindrical ; 
aperture channeled in front; interior with continuous 
ridges on the columella and whorls. 
Fossil, 150 species. Inf. oolite—U. chalk. Britain, 
France, Germany, Spain, and Portugal. They are 
most abundant, and attain the largest size to the 
south; and usually occur in calcareous strata, asso- 
ciated with shallow-water shells. (Sharpe.) 
Sub-genera. 1. Nerinea. Folds simple: 2—3 on 
the columella ; 1—2 on the outer wall; columella solid, 
or perforated. Above 50 species. 
2. Nerinella (Sharpe), columella solid; folds simple ; 
columellar, 0O—1; outer wall, 1. 
3. Trochalia (Sharpe), columella perforated, with 
| one fold; outer wall simple, or thickened, or with one 
fold; folds simple. 
4, Ptygmatis (Sharpe), columella solid or perforated, 
Fig. 9s.* usually with 3 folds; outer wall with 1—3 folds, some 
of them complicated in form. 
P FASTIGIELLA, Reeve. 
Type, ¥. carinata, Reeve. 
Shelé like turritella; aperture with a short canal in front 
(Cuming Museum, and British Museum). 
Fossil, Eocene. Paris (Cerithium rugoswm, Lam.). 
APoRRHAIS, Aldrovandus. 
Etymology, aporrhais (Aristotle), ‘‘ spout-shell,” from aporrheo, 
to flow away. 
* Fig. 98. Nerinea trachea, Desl., partly ground down to show the form of tite 
interior. Bath oolite, Ranvile, Communicated by John Morris, Esq. 
