118 
ON THE OCCURRENCE OF THE FISSURELLID 
GENUS ZIDORA IN AUSTRALIAN WATERS, 
By Proressor Rare Tare. 
[Read May 1, 1894.] 
The genus Zerdora was instituted by A. Adams in 1860, for 
the reception of two Japanese shells having the outer aspect of 
Emarginula and an internal shelf as in Crepidula. Reeve in 
his monograph, 1873, figures the two species described previously 
by Adams. Two species referrable to this genus occur in 
Pliocene strata in Italy, upon one of which Sequenza, 1880, pro- 
posed his genus Crepiemarginula, which Boog Watson, “ Chal- 
lenger Report,’ 1886, relegates to a synonym. Mr. Beddome, 
Proc. Roy. Soc. Tasm. for 1882, p. 169 (1883), founded his genus 
Legrandia on an undoubted example of Zidora. Boog Watson, 
op. cit., added another species to the genus, from the West Indies, 
making four in all known in living creation. It is not at all 
improbable that the shell I am about to describe is conspecific 
with Beddome’s Legrandia Tasmanica. Fischer, “ Manuel de 
Conch.,” 1885, emended the spelling of the generic name to 
Zidora. 
The genus is of extreme interest from a morphological point 
of view, which is enhanced by the beauty of ornament and rarity 
of occurrence of the shells. The animal of Zdora is unknown, 
and despite the analogy that the shell presents to Emarginula 
and Puncturella, Mr. Boog Watson is disposed to view the shell 
as an internal one, and that “its true place will probably be 
found among the Opisthobranchiata, perhaps in the neighbour- 
hood of Pleurobranchus.” 
The shells of the living species have hitherto been obtained 
only from moderately deep water. 
ZipoRA LEGRANDI, spec. nov. (1894). 
Shell depressedly conical, cap-shaped, white, delicate, elliptic- 
oblong in basal outline, rounded behind, truncately rounded and 
deeply cleft in front, with a narrow sunken fissural band extend- 
ing to the apex; back depressedly convex ; apex minute and 
short, hooked and somewhat adpressed, almost reaching the pos- 
terior margin. 
The ornament consists of concentric threadlets and obliquely 
radial threadlets, which produce an elegant cancellation of 
rhombic spaces ; in the apical region the ornament is extremely: 
fine, but beyond it the cancellation is visible to the unaided eye 
