135 
NoTES ON SoUTH AUSTRALIAN MARINE MOLLUSCA, 
WITH DESCRIPTIONS ОҒ NEW SPECIES, PART 1. 
By Jos. C. Verco, M.D. (Lond.), F.R.C.S. (Eng.), etc. 
[Read August 2, 1904.] 
PLATE XXVI. 
Dentalium intercalatum, Gould. 
Proc. Bost. Soc. Nat. Hist. vii., p. 166 (1859); Otia, p. 4494 
Sowerby in Conch. Icon., xviii., pl. vii., fig. 45 (1872). Type lo- 
cality, China Seas (North Pacific Expl. Kxped.).  Pilsbry in 
Tryon's Manual of Conchology, vol. xvii., p. 25, pl. xi., figs. 88, 89. 
D. Bednalli, Pilsbry & Skarp, Man. of Conch., vol. xvii., p. 248, pl. 
xxxix., figs. 1, 2, 8; type locality, St. Vincent Gulf (W. T. Bed- 
nall). D. octogomum, Angas (non Lam.), P.Z.S., 1878, p. 868, 
Henley Beach, S.A. 
Angas misidentified our shell from Henley Beach as P. 
octogonum, Lam., and cited it as a South Australian shell in 
P.Z.8., 1878, p. 868. Pilsbry & Sharp, in Tryon's Man. of 
Conch., vol xvii, p. 248, described a shell under the name 
of D. Bednalli, from St. Vincent Gulf, sent to them by Mr. 
W. T. Bednall. This name would stand, were it not that 
specimens of our extremely variable species are inseparable 
from D. intercalatum, Gould, 1859, which has priority. 
I have examined more than three hundred individuals, 
dredged by me in St. Vincent and Spencer Gulfs, Investiga- 
tor Strait, and Backstairs Passage. They have been taken 
alive at all depths between eight and twenty-two fathoms, 
chiefly in muddy bottoms. I have vainly endeavoured to dis- 
cover more than one species among them. They are exceed- 
ingly variable, and were it not for intermediate forms, quite 
a dozen species might be created. 
Its length varies, of course: firstly, with its age; indi- 
viduals when very young are only 5 millimetres, when senile 
37; secondly, with the amount of its posterior end which has 
been removed, so that a stouter, older shell may not be so 
long as another which is evidently younger and has not suf- 
fered so much truncation. 
Its curvature is also very variable. In its early stage of 
growth it is well curved, but becomes gradually, though 
markedly, less so as it gets older. Since the posterior end is 
progressively removed, the mature shell has an appearance 
quite different from that of the immature, being nearly 
straight and bluntly truncated, instead of well curved and 
posteriorly acuminate. The same individual in its two ex- 
treme stages of growth, without the controlling intermediate 
