79 .. 
S.A* NAT, VOL. XV. 
June 12th, 193 4. By Bernard C. Cotton and F. K. Godfrey. 
C. undatus Lamarck 1816 ( Monodonta ). PI. 1, fig. 2. 
(— Irochus smithii Wood). Large, depressed conoid, excavat¬ 
ed, ^false umbilicate; cinereous or rose coloured, radiately striped 
with brown or black, the stripes sometimes broken into irregular 
maculations, especially on base; protoconch acute, eroded;" fol¬ 
lowing whorls finely granose in spiral series, about ten or twelve 
spiials on each whorl; last whorl with about thirty spiral gran- 
ose ridges, very close and fine upon and below the periphery, 
coarser above and around the umbilicus, the interstices obliquely 
striate; whorls about six, convex around the upper part, then 
flattened, obtusely angulate at the periphery, sharply cannated 
in the juvenile, the base flattened, concave towards the centre: 
sutures subcanaliculatc; last whorl somewhat deflected anteriorly; 
aperture oblique, tetragonal, outer and basal lips thickened and 
plicate within; columella oblique, inserted nearly in the bottom 
of the bioad umbilical excavation, its edge reflexed and bearing 
about ten denticles, twisted near the insertion, terminating be- 
loy in a simple tooth; parietal tract wrinkled; umbilicus with a 
plicate border, and. in the middle a strong, sometimes crenulate, 
spiral funiclc. Height 16. diam. 28 mm. Xot common, Port 
\\ illunga, Corny Point, Levens, and fine specimens alive at 
Middleton. Dredged dead, Beachport 40-150 fathoms. Also 
Western Australia—King George Sound to Rottnest. (Type- 
locality—we designate Middleton, Encounter Bay, South Aus¬ 
tralia). The largest Clay cuius, handsome, solid, purple, red, 
with small black spots on the granulations; the enamel of the 
moe-h is often much spread over the base as a transparent film,. 
In fuily adult shells three sharp denticulations are found on the 
middle third of the edge of the outer lip, terminating three alter¬ 
nate lines of spiral granulations. The inner surface of the outer 
lip, and of the expanded basal callus is smeared with rusty 
brown. 1 Its diameter at the base may reach 34 mm., and in 
some adults is only 27 mm. In immature shells of 27 mm. diam. y 
the columella, and the margin of the umbilicus, and the spiral 
ridge within it are smooth, the ledge between the latter two is 
brown and between the first and" last white. The following 
shows height and width in mm. at different beaches, and their 
percentage of height to width, and the gradual increase in height 
from Tasmania and Victoria through South Australia, and through 
Esperance and Albany to Ellensbrook and Rottnest, where also- 
the shells are heavier. 
