Nissan Island Mollusca — Dell 
329 
Fig. 2. a, Shell of Partula (. Melanesica ) cf. carteriensis (Q. and G.) (Nissan Island, 17.8 X 9-8 mm.), b-d, Apical 
basal, and frontal aspects of the shell of Papuina ( Pinnadena ) periwonensis n. sp. (holotype, 28.0 X 19.1 mm.). 
Partula (Melanesica) cf. carteriensis 
(Q. and G., 1832) 
Fig. 2 a 
A species of 'Partula was comparatively 
common on the island living on vegetation. 
The collection contains three specimens. 
They are close to P. carteriensis (Q. and G.) 
as described and figured by Pilsbry (1909: 
298, pi. 36, figs. 15, 16) and the geographical 
position of Nissan in relation to New Ireland 
makes it very probable that they are closely 
related if not identical. The spiral sculpture 
is very fine as described for P. carteriensis (Q. 
and G.). Table 3 gives shell measurements of 
Pilsbry’s specimens and three from Nissan. 
The systematics of the group in the Solomon 
Islands is so uncertain that a figure is given 
of a Nissan Island specimen. The tooth on the 
par'etal lip is absent in the other specimens. 
Opeas gracilis Hutton, 1854 
A number of specimens were collected 
under rotten wood near the lagoon at Tan- 
galan Plantation. This species is a tropical 
cosmopolite and has been recorded from 
many of the islands of the Solomon group. 
DISCUSSION 
Thirteen species of land snails are herein 
recorded from this small island and it is 
highly probable that other forms will be col- 
lected in the future. It is, however, unlikely 
that any large species were missed. The re- 
lationships of th's fauna are, as might be 
expected, with both the Bismarck Archipelago 
and with the other Solomon Islands. Four of 
the species appear to be endemic to the island 
but for three of these ( Orpiella nissani , Gyropena 
nissani and Paludinella solomonensis ) this is 
probably an apparent, rather than a true en- 
demism. So little is known of the molluscan 
fauna of the northern Solomons, especially 
the smaller forms, that little value can as yet 
come from such comparisons. It is more 
likely that Papuina periwonensis is truly en- 
demic although again it could quite easily 
