138. 
S.A. NAT., VOL. XIV. 
August 31st. 1933. 
South Australian Shells. 
DENTALIIDAE. 
Shell tubular, curved, with the greatest diameter at the an- 
terior aperture, and tapering evenly to the posterior aperture. 
J3istribution — All seas, from the littoral to moderate depths. 
Fossil — Ordovician, but most abundant from the 'Cretaceous- 
where very large species occur. Animal having the foot conical,, 
with a laterally and dorsally interrupted encircling sheath. Dif- 
ferences between this famiy and SiphonodentaUlclae have been 
outlined under class Scaphopoda. 
Dentalium Linne 1758. An elongate tube open at both 
ends, increasing in diameter from apex to aperture, section of 
maximum diameter being coincident with the peristome; almost 
straight to strongly curved; usually with longitudinal riblcts or 
engraved lines, especially near the tip; these may vary In number 
from six to sixty or more: ribs or riblets In the apical portion 
eften increased later by addition of others intercalated between 
them; sculpture frequent!}' disappears in the anterior portion; 
sometimes fine transverse lirae occup}' the spaces between the 
ribs or even cross them; or the intercostal surface may present 
a fine reticulate plan of excessively minute sculptural elements; 
in some groups there are no sculptural features whatever; em- 
br\ onic portion of apex very minute and fragile, and nearly al- 
wa}'s lost in very young specimens; apical section remaining 
be round or angular in section; apical opening usually modified 
bv a slit or notch of varying width or depth and variously placed 
in different groups; or the opening may be simple without notch 
or slit; shell varies from minute needle-like forms to those of four 
or five inches in l.'ngth, in thickness from fragile to heavy and 
solid; in texture from soft and chalky to hard porcellanous or 
glassy; in colour from greenish, reddish, or yellowish species to 
pure white, the latter greatly predominating; the shells ma}' be 
translucent to opaque, dull lustreless to the most highly polished 
and glistening surface. Type — D. elt^phantlnum Linne (Amboyna) 
Animal shaped like its shell, elongate, wrapped in a mantle 
Cipen at both ends; from larger end a pointed cylindrical foot 
nia} be protruded or almost wholly withdrawn; without tentacles- 
or eyes; just hack of the mouth is a cluster of thread-like ap- 
pendages enlarged into spoon-shaped terminals (captaculae) — the 
exact function of these is not definitely understood, but they arc- 
supposed to catch and hold the food, consisting largeh' of fora- 
minlfera and other minute organisms; the liver is two-Iobed, the 
gonad simple; heart of cnc ventricle; without gills; excretory op- 
enings in the forward part of the mantle cavity, but the escape 
