y 
South Australian Shells. 
S.A. NAT., VOL. XVI, 
Dec. 15 , 1934 . 
unicoloured; protoconch usually somewhat eroded, fairly acute; 
whorls four to five, slightly convex, and usually somewhat eroded, 
the whole uniformly weakly spirally ribbed with seven or less ribs 
on the body whorl; aperture oblique, outer lip thick, lirate, black 
margined within; columella short, slightly oblique, weakly dentate 
at the base with frequently two denticles in the adult, but often 
the two fuse forming one denticle. Height 32, diam. 28 mm. 
Type locality — Gulf St. Vincent (South Australia). Reg. No. 
D 1 1289 S.A. Mus. Very common, general, on exposed rocks, 
South Australia; less common in Western Australia. This spe- 
cies is easily distinguished from the eastern Australian A. con- 
stricta Lamarck, by its much less coarse sculpture, the type il- 
lustrated shows the maximum development of the spiral ribs seen 
in Flindersian specimens. The present species is also much small- 
er than A. constricta and more solid. Eastern Tasmanian speci- 
mens of A. constricta average one-third larger in size, having ele- 
vated keels and are much thinner than A. torn. Distinguished 
from A. zebra Menke, by the coloration, the slightly more valid 
and separated ribs, which are noticeably close on the base of 
A. zebra which is also smaller. 
A. zebra Menke 1829 ( Monodonta ) (not A. obtnsa Dill- 
wyn 1817, a common Sydney shell: not Trochus zebra Wood: 
~ Labio porcatus A. Adams 1851). Id. 1, fig. 2. “The Striped 
Austrocochlea.” Imperforate, thick, solid, lustreless; whitish or 
covered with a thin greenish-yellow cuticle, indistinctly longi- 
tudinally striped with black or dull red, the stripes sometimes 
zigzag; spire conic, acute; whorls six to seven, convex, obliquely 
striated and weakly spirally ridged; four to five ridges on the 
penultimate, eight to twelve on last whorl not so prominent as 
in A. torri or A. constrict a, and closer, especially upon the base; 
aperture as in A. torn and A. constricta ; outer lip lirate or 
smooth within; columella bearing an inconspicuous blunt tuber- 
cle near base. Height 25-34, diam. 22-25 mm. Common on 
rocks between tide marks, South Australia and Western Australia. 
(Type locality — South Australian Coasts). A. zebra is distin- 
guished from A. torri by the more numerous, less salient spiral 
ridges, and by the colour pattern of dull red or black stripes 
alternating with white; the cuticle is usually rubbed off in adults, 
causing the underlying white to replace the yellow, and intense 
black the red, of fresh shells. There is a dwarfed variety from 
the border of the mangrove swamps which can bear the varietal 
name porcala A. Adams. It is more elongated than typical 
zebra . aperture less dilated, columellar tubercle obsolete. Many 
collectors have their examples of zebra Menke, labelled obt.usa 
Diliwyn, which is a New South Whiles shell and thicker, heavier, 
