HORN EXPEDITION—MOLLUSCA. 
091 
X 
and radula (Fig. B). 
The penis is distant 
from the tentacle, 
and is two-pronged. 
Except that the 
operculum seemed 
corneous instead of 
calcareous, the ob¬ 
served features of 
this species har¬ 
monised generically 
with those of Bith- 
inia ientaculata. 
Micpophyupa hemiclausa, Tate. 
In a matchbox of small shells and soil from Palm Creek, I detected several 
examples of Planispira he/niciausa, Tate. Most contained the dried remains of the 
animal. These I soaked in water for a day in the hope that life was not extinct 
in all, but without success. I then crushed some of the shells and boiled the 
animals in potash to extract the radula. The minute size of this rendered the task 
one of great dithculty, and I 
failed to distinguish the denti¬ 
tion as clearly as 1 wished. The 
jaw (Fig. C) appeared to be 
composed of numerous separate 
plates ; the odontophore (Fig. C) 
to contain about seventy trans¬ 
verse rows, each row numbering 
about fifteen teeth. The rachidian is tricuspid, a long slender mesocone flanked 
by two small cusps. This type is repeated in the laterals; the marginals 
are serrated. As I failed to see plainly the basal plates, I have not drawn them. 
T have identified as AI. hemiclausa a shell collected at Bowen, Queensland, by 
INIr. A. Simson, who tells me that the species was also taken at Cardwell by Mr. 
Beddome. The shell characters of this species indicate its position in the genus 
Alicrophyura, the only previously-described species of which is M, microphis, 
Crosse, inhabiting New Caledonia and the Loyalty Archipelago. Judging from 
figures the Australian shell bears a strong, if superficial, likeness to the American 
Pynimidula lineata. The genus would seem from its distribution and anatomy 
to be of high antiquity and of Antarctic origin. It is, perhaps, one of the most 
primitive of Australian snails. 
