140 . 
S.A. NAT., VOL. XIV. 
August 31st. 1933. 
South AustraUan Shdls. 
Eudentalium subeeii. uov. Shell small; tube square at and 
near the apex, angular at the aperture; primary ribs serrate, in- 
tervals ribless. I'ype — D. quadricostatum Brazier, a South Aus- 
tralian shell, although also rej'orted from north-east .\ustralla and 
New Guinea. 
Episiphon Pilsbry & Sharp 1897 (Subgenus). Shell very 
small, slender, rather straight, needle-shaped, slightly tapering, 
thin, fragile, glossy, smooth, and without longitudinal sculpture; 
apex with a projecting pipe or is a simple orifice; no slit, rarelv 
a notch. Type — D, sozverbyi Guiiding 1834, from the Caribbean 
Sea. Here we place D. virgula Hedley, D. hyper he mUeuron 
Verco. 
D. intercalatum Gould 1859 D. octogonuni Angas 1878, 
not Lamarck). ^*4’he Intercalated Dentalium.'’ Strongly curved 
and conspicuously tapering In its earlier half, the latter half 
nearly straight and less tapering; white, lustreless; at and near 
the apex, hexagonal in section, the angles rather sharp and a little 
projecting, intervals nearly flat; not far from apex a secondary 
riblet arises in each of the two faces on the outer curve, and 
somewhat later the lateral faces and those on the concave side 
are similarly divided; the secondary riblets gaining rapidly in 
strength, and on the latter part of the shell equal to the six pri- 
mal'}' ribs; apical orifice circular, about half as wide as the trun- 
cated apex. Length 19, diam. at aperture 2.25, at apex 0.9 mm. 
General, and not uncommon, beach and down to 300 fathoms, 
chiefly in muddy bottoms. Also Western Australia — King George 
Sound to Geographe Bay. (Type locality — China Seas). Kx- 
ceedingly variable. Length may reach 37 inm. The amount 
truncated varies so that a stouter, older shell, may not be so 
long as another which is evidently younger and has not suffered 
so much truncation. Curvature varies; since tlie posterior end is 
progressively removed, the mature shell appears different irom 
that of the immature, being nearly straight and bluntly truncated 
instead of well curved and posteriorly acuminate. Usually the 
ribs become more numerous with age, the increase being effected 
by intercalation and by rib splitting. Generally in the centre 
of an interspace a riblet arises, and gradually enlarges until it 
equals the original ribs. The stage of growth at which inter- 
calation begins varies not only In different shells, but in the 
several interspaces of the same shell. Besides the ^ secondary 
riblets, eventually tertiary riblets may arise in their interspaces 
and further multiply the costations. In any position, two equal 
riblets, instead of only one, may develop simultaneously in an in- 
terspace. Further a groove begins to form a rib, and gradually 
