468 MOLLUSCA SUB-KINGDOM VI 
Trochalia, Sharpe (Cryptoplocus, Pict. and Camp.), (Fig. 923). Turreted to 
5 

Fic. 923. Fic. 924, 
Trochalia consobrina, Zitt. A, Nerinea Defrancei, @Orb. Coral-Rag; Coulanges sur Yonne. 3B, N. 
Tithonian 3s Stramberg, dilatata, d’Orb. Coral-Rag; Oyonnax, Ain. C-E, N. Hoheneggeri, Peters. 
Moravia. Longitudinal section. Tithonian ; Stramberg, Moravia. C, 2/3. D,1/;. £, Longitudinal section. 
pyramidal, usually smooth and imperforate. The inner lip only has a strong, simple 
fold. Jura and Cretaceous. 
Nerinella, Sharpe (Pseudonerinea, Loriol). Turreted, imperforate. Outer lip and 
sometimes also the columella with a simple fold. Jura. 
Nerinea, Defr. (Fig. 924). Turreted or pyramidal, usually 
imperforate. Columella invariably, and inner and outer lips 
generally, with simple folds.) Jura and Cretaceous ; maximum in 
the Coral Rag (Upper Jura). 
Ptygmatis, Sharpe (Fig. 925). Like the last, except that the 
folds on both lips and the columella are 
complicated by secondary constrictions and 
branchings. Jura and Cretaceous. 
Itieria, Math. (Fig. 926). Elongate-oval, 
usually umbilicate. Spire short, sometimes 
insunken. Body whorl very large, more or 
less enveloping the preceding. Columella 
and both lips with folds. Jura and Cre- 
taceous. 4 

Fic. 925. 
Ptygmatis pseudo- 
bruntrutana, Gem- 
Fic. 926. 
Family 17. Cerithiidae. Menke. 
mellaro. Tithonian ; Itieria Staszycii, Zeuschner. 
Inwald, Carpathia. Tithonian; Inwald and : 
Vertical section. Stramberg. Shell turreted ; aperture elongated, oval, 
or quadrilateral, anteriorly with short canal. 
Outer lip often thickened and reflected, or thin and sharp. Colwmella sometimes with one 
or two folds. Operculum horny, spiral. Marine and brackish water. Trias to Recent. 
More than 1000 living, and about 500 fossil species are known, the latter being 
most numerous in the Eocene. The earliest forms are usually of small size, and have 
a nearly entire peristome. 
