A revision of the Australian fossil species of Zoila (Gastropoda: Cypraeidae) 
7 
Figure 2. Protoconchs. A, Zoilaplatypyga (McCoy, 1876), P308781, x 7; B, Zoila gigas (McCoy, 1867), P308792, x 3.6; C, Zoila viathomsoni sp. 
nov., WAM x 10. 
Siltstone. The associated fauna comprises large numbers of 
siliceous sponges. The protoconch observed in cross-section 
(fig. 2C), is paucispiral and slightly deviated from the axis of the 
teleoconch, unlike the multispiral protoconchs of Cypraeorbis 
species. The general size and shape of the shell resembles that 
of Cypraeorbis medius, C. bartonensis and C. ventripotens; 
however, the fossula (fig. 5L) is not the same as that present in 
these species. The fossula is very wide and prominent, projecting 
into the aperture. It is more elongate than that of these three 
species, does not have a prominent notch and the anterior border 
is not thickened. In general shape and concavity, it resembles 
those in Zoila friendii and Z. decipiens. Zoila viathomsoni 
bears a close resemblance to Z. chathamensis (Cernohorsky), 
late Paleocene to early Eocene, Chatham Islands, New Zealand, 
but it is not as tumid, has much finer and more numerous 
apertural teeth, the posterior labral border of the posterior canal 
is more produced posteriorly and it is only about two-thirds the 
size. Given the similarities, Z. chathamensis is a possible 
ancestor of Z. viathomsoni sp. nov.; Z. chathamensis is the 
earliest known representative of the genus. 
Zoila viathomsoni bears some resemblance in size and 
shape to Lyncina (Austrocypraea) onkastoma Yates, 2009, 
recorded from the early Oligocene of South Australia, but 
lacks the well-defined anterior rostrum of L. (A.) onkastoma, 
as well as the prominent notch on the fossula. 
Etymology. Latin via road. 
Zoila didymorhyncha sp. nov. 
Figures IE, 6A-E, I 
Description. Shell solid, small for genus, elongate, subfusiform; 
base relatively flat, but rounded on either side of aperture. Spire 
not visible. Posterior canal long, with rounded sides, sunk into 
massive rounded posterior rostrum formed by extensions of 
inner and outer lips. Anterior canal long, with rounded sides, 
sunk into a thick, rather flat rostrum. Aperture somewhat 
sinuous; outer lip with 10-24 well-developed teeth extending 
along entire lip; teeth completely obsolete on one specimen. 
Columella lip with 3-26 well-developed teeth extending along 
entire lip on most specimens; teeth obsolete on one specimen. 
Fossula moderately developed, very shallow, bounded 
anteriorly by a small, weak, terminal ridge. 
Dimensions. 
L 
W 
H 
LT 
CT 
Holotype 
P302687 
62 
31 
25 
24 
26 
Paratype 
P302685 
80 
32 
27 
10 
3 
P302686 
64+ 
32 
26 
22+ 
25 anterior 
canal broken 
Type locality. PL3022 cliff section at Addiscot Beach, beds 
B109-107, southwest of small gully, clay overlying Demons 
Bluff Formation, Victoria. AMG Torquay BT619490. Jan Juc 
Formation. Early Janjukian. 
Type material. Holotype P302687, collected T.A. Darragh, 4 
December 1985; paratype P302685, collected T.A. Darragh 8 
May 1990. 
Time range. Early Janjukian, Late Oligocene. 
Occurrence and material. PL3022 Addiscott Beach (three 
specimens). 
