Treasury Is. Mollusca — Dell 
425 
Height, 3-91 mm.; diameter, 2.18 mm.; 
height of aperture, 1.64 mm. 
holotype: (M. F. 2514) in Dominion Mu- 
seum, Wellington. Collected by N. Gardner, 
1944. 
locality: In leaf mould from ridge above 
Seveke River, Mono Island, Treasury Group. 
This and the following species are appar- 
ently the first records of the genus from the 
Solomon Islands. Species of Diplommatina 
have not as yet been recorded from the Bis- 
marck Archipelago. The genus is probably 
quite widely distributed in both groups, but 
smaller land snails have undoubtedly been 
neglected in both groups. Thorough con- 
chological exploration, especially of the larger 
islands, would certainly yield a rich harvest. 
Diplommatina aerari bears a striking resem- 
blance to Palaina commixta Rensch from New 
Britain but differs of course in the possession 
of the columellar tooth and in the outline of 
the aperture. 
Diplommatina solomonensis n. sp. 
Fig. la 
Shell small, dextral, subcylindrical but up- 
per whorls gradually tapering to a widely 
rounded apex, pale yellowish brown. Whorls 
six and a half, regularly increasing to about 
the fourth whorl, suture impressed. The last 
two whorls approximately the same width. 
The first one and a half whorls sculptured with 
very fine axials, followed on subsequent 
whorls by fairly regular, numerous, raised 
lamellae, microscopic spirals between the 
lamellae. Body whorls flattened in the middle 
above the aperture. 
Aperture rounded, entire, flared outwards, 
closely appressed to body whorl at the flat- 
tened portion. A small, but prominent, tooth 
on the columella side of the peristome. Peris- 
tome margin wide, slightly channelled. The 
region behind the peristome on the body 
whorl considerably thickened, the thickened 
portion clearly marked off by a prominent 
raised axial rib. 
Fig. 1 . a, Diplommatina solomonensis n. sp., holotype 
(3.09 X 1.45 mm.); b, Diplommatina aerari n. sp., 
holotype (3.91 X 2.18 mm.); c, Palaina gardneri n. sp., 
protoconch; d , Palaina gardneri n. sp., holotype (4.64 
X 2.27 mm.). 
Height, 3.09 mm.; diameter, 1.45 mm.; 
height of aperture, 1.18 mm. 
holotype: (M. F. 2515) in Dominion Mu- 
seum, Wellington. Collected by N. Gardner, 
1944. 
LOCALITY: In leaf mould from ridge above 
Seveke River, Mono Island, Treasury Group. 
Diplommatina solomonensis n. sp. differs at 
sight from D. aerari in being dextral, in having 
a much narrower shell, and a very different 
spire outline. 
The remaining 14 species are members of 
the family Helicinidae. The forms of this 
family from the Solomons and indeed from 
the Pacific islands generally are urgently in 
need of revision. Wagner’s works on the 
genus are not available in this country but 
the figures and descriptions that have been 
published are usually totally inadequate for 
the fine discrimination of species. Figures 
such as those of Reeve are too small and 
indefinite. The systematics of the group is a 
problem that can be solved only by those 
having access to the type specimens and to 
adequate, carefully localized series of spec- 
imens. The following species have been re- 
corded from the Treasury Group but the 
identifications should be taken as provisional 
only. 
