THE MOLLUSCA—HEDLEY. 403 
PHENACOLEPAS SENTA, Sp. nov. 
(Fig. 1). 
iBiiee, Ie 
Shell cap shaped, with a protuberant and overhanging posterior 
apex, the earlier portion thin and translucent, the older solid 
and opaque; adult shell asymmetrical by reason of a slight 
spiral twist. Colour white. The nepionic shell is very smooth 
and glossy sharply contrasting with the dull surface of the 
remainder, depressedly turbinate, apparently two whorled but 
swallowed past the nucleus by the older shell. Sculpture :—on 
the part next the nepionic shell there are circular growth lines, as 
these diverge wider their interstices are crossed by longitudinal 
lines which develop later into low small rounded ribs parted by 
slight furrows, these are reticulated by two series of fine raised 
threads crossing at right angles. Upon these ribs arise in quin- 
cunx order a series of V-shaped thorns, the limbs of which are 
directed anteriorly. A portion of the dorsal surface immediately 
above the posterior base is selected in the accompanying figure 
for illustrating this feature. Finally the limbs increase till they . 
meet those of their neighbours and enclose a rhomboidal space, 
thus the marginal part of the shell becomes cancellated by a raised 
network, oblique both to the line of growth, the axis of the shell 
and the earlier sculpture. The minute transverse thread lines 
persist to the aperture. 
Aperture subcircular, the edge when adult is broadened and 
finely crenulated. Interior glossy, the exterior sculpture visible 
through the shell. Muscular impressions are a right and left 
adductor scar and a narrow horse shoe marking the head line a 
little within the lip. Length 6, breadth 44, height 3 mm. 
Eight empty shells from sand on the beach of Funafuti 
lagoon. 
