SUB-ORDER B PLATY PODA 475 
Distortrix, Link. (Persona, Montf.). Tertiary and Recent. 
Ranella, Lam. (Fig. 960). Like Tritontwm, but with two opposite varices, which 
are continuous over all the whorls. Tertiary and Recent. 
Superfamily 4. RACHIGLOSSA. Gray. 
Radula reduced to three teeth or to one tooth in a transverse series. 
These are carnivorous marine forms, which have their initiation in the Mesozoic, 
become somewhat numerous in the Cretaceous, and form an important element of the 
Tertiary and Recent faunas. 
Family 1. Columbellidae.  Troschel. 
Shell small, ovate to fusiform, covered with epidermis, imperforate. Aperture narrow, 
canal short. Outer lip denticulated internally, thickened in the middle. 
Tertiary and Recent. 
The typical genus, Colwmbella, Lamarck (Fig. 961), attains its 
maximum distribution in the Tertiary and Recent seas. It is divided 
into a number of sub-genera. 

Family 2. Buccinidae.  Troschel. 
Fic. 961. 
Shell elongate-oval, covered with epidermis. Aperture wide, with — Columbella curta, 
short canal. Outer lip sharp or thickened. Operculum horny.  Cre- Tae Pater 
taceous to Recent. Ve 
Buecetnum, Linn. Inflated, smooth, or transversely ribbed. Spire moderately 
high ; aperture wide; canal short, wide, open. Outer lip sharp and thin, inner lip 
somewhat callous. Distributed principally in waters of the more 
northerly zones (6. wndatwm, Linn.). Fossil in the Crag and 
Pleistocene. 
Cominella, Gray (Fig. 962). Usually spirally ribbed. The last 
whorl somewhat depressed beneath the suture, so that the aperture 
forms a small groove 
posteriorly. Outer lip 
sharp or crenate intern- 
Cominella cassidaria, ally. Upper Cretaceous 
A.Braun. Oligocene; to Recent. 
ape haa Pseudoliva, Swains. 
(Fig. 963). like the 
last, but outer lip with a small basal 
tooth or notch which corresponds to a 
groove on the body whorl. Upper Cre- 
taceous to Recent. 
Pisania, Bivona (Pisanella, vy. Koenen ; 
Taurinia, Bellardi). Elongate-ovoid, spire 
moderately high. Whorls smooth or 

Fic. 962. 

spirally striated. Outer margin thickened, Fic. 963. Pic. 964. 
notched internally. Tertiary and Recent. — Pseudoliva Zitteli, Petho. Pollia sublavata, Bast. 
: ee Yr 5 2 iy. Upper Cretaceous ; Fruska sp. Miocene; Enzes- 
Pollia, Gray (Canthat US, Bolten >» Gora, Hungary. feld, near Vienna. 
Tritonidea, Swains.), (Fig. 964). Oval, 
inflated ; spire and aperture of about equal length; surface usually spirally ribbed 
and transversely folded. Columella often with weak transverse folds ; outer margin 
thickened, crenate internally. Aperture posteriorly with a short canal. Tertiary 
and Recent. 
