S.A. NAT., 
VOL. XVIII. No. 2. 
By TOM IR?:UALE. 
29. 
Family Hadridae. 
Hereunder are placed the shells previously regarded as 
Badistes and Thersites. It is not definite that these are closely 
related to the shells hitherto classed as Badistes and Thersites, 
but conchologically they recall those groups, and until we know 
more about the anatomy of these molluscs they may remain here. 
Then owing to the relationship of the anatomy are placed 
here many shells smaller and generally unlike in appearance for 
which I had provided the genera Semotrachia and Vidumelon. 
Hedley separated ‘^Thersites^^ from “Xanthomelo7i” by means 
of the generative system, but his alliances by this criterion appear 
very unnatural, and the conchological features deserve more 
consideration, a conclusion Hedley himself later reached. For 
the present however Semotrachia may be placed here, while the 
extraordinary Vidumelon gives no clue, but on account of the 
apertural formation it may be more closely related to this family 
than the next. Another genus of difficult location is Cupedora 
which is conchologically similar to Meracomelon, so much so that 
the members have been commonly confused, yet in some ways 
it recalls some of the aberrant members of Pleuroxia, which is 
supposed to belong to the other family. 
Key to Genera. 
Shell almost imperforate, helicoid, thin, granulose throughout 
Exilibadistes. 
Shell umbilicate, flattened helicoid, granulose generally, 
coloration banded M eracomelon. 
Shell similar in shape to members of the preceding genera, 
but with coarse radial plicae, and scattered gran- 
ulation and earlier whorls sub-keeled with an ante- 
peripheral depression Cupedora, 
Shell small, subdiscoidal, surface more or less granulose, 
mouth oblique, with expanded lips and almost free 
with a constriction behind the lip and generally a 
wide umbilicus Semotrachia, 
Shell flattened, rounded whorls, subdiscoidal, many whorled, 
umbilicus very narrow, mouth elongate, edges re- 
flected ' Vidumelon, 
Genus Exilibadistes. 
1933. Exilibadistes Iredale, Rec. Austr. Mus., Vol. XIX, p.S2, 
August 2. 
Orthotype Helix bednalli Br^izler— Helix sutilosa Deshayes. 
Shell very similar to that of jervisensis Quoy and Gaimard, 
the “type” of '‘Badistes” in general appearance so that Des- 
