S.A. NAT., 
VOL. XVIII, No. 2. 
49. 
By TOM IREDALE. 
1896, Angasella oligopleura Tate, Rep. Horn Sci. Exped. Centr. 
Austr., pt. II, Zoo!., no text, p.219, pi. XIX, fig. 39, 
February. “Flinders Range S.A.’’ error (interchange of 
localities with T, zailpenensis) . 
Pleuroxia radiata. 
1905. Xanthomelo7i radiatum Hedlev, Trans. Roy. Soc. South 
Austr., Vol. XXIX, p.l63, ph' XXX, figs. 4, 5, 6, Decem- 
ber. Mount Davies, Tomkinson Range, and Musgrave 
Ranges, Central Australia. 
Pleuroxia lemani. 
1916. Angasella lemani Gude, Proc. Malac. Soc, (Lond.), Vol, 
XII, p-41, fig. in text, March 20. Cape Borda, Kangaroo 
Island, South Australia. 
Pleuroxia adcockiana. 
1894. Hadra adcockiana Bednall, Trans. Roy. Soc. South Austr., 
Vol. XVTII, p.l90, fig. in text, November. Tempe 
Downs Station, Central Australia. 
1896. Thersites adcockiana Tate, Rep. Horn. Sci. Exped. Centr. 
Austr., pt. II, ZooL, p.l96, pi. XIX, fig. 26, February. 
Throughout the Larapintine area, exceedingly variable; 
three forms discussed and described but not named. 
Bednalhs shell was deeply umbilicated measuring “Major 
diameter, 14 mm.; minor, 12 mm.; altitude, 8 mm.; height of 
aperture, 7 mm.; length, 7.5 mm.; diameter of umbilicus, 2 mm.” 
Many specimens were collected by the Horn Expedition and 
unfortunately the lots were not kept separate and thus Tate 
reported as above noted but undoubtedly more than one species, 
not to mention subspecies, appear In the series now classed under 
adcockiana. One series consists of small shells with open umbili- 
cus, and another comprises shells larger with umbilicus almost 
closed while the sculpture varies also. The shells with the 
narrow open umbilicus should carry BednalFs name, and a series 
from Krickaueff Range have the umbilicus hidden so that less 
than 1 mm. width shows. BednalFs shell is very finely sculptured 
with striae, but in the Krickaueff shells the sculpture becomes 
notable ribbing the shell more elevated and a specimen selected 
as type of the new species, truca, PI. II, fig. 8, measures 16 mm. 
in diameter by 12 mm. in height. Other shells which unfortun- 
ately have no other locality save Central Australia vary in the 
other direction, the sculpture becoming stronger, the shell flat- 
tened and the umbilicus more open. 
