18 AUSTRALASIAN ANTARCTIC EXPEDITION. 
About forty large and several minute shells belonging to a new species of 
Liothyrella were found on a large flat stone brought up on a fishing line, in Cook Strait. 
The depth cannot have exceeded 200 fathoms and may have been much less. Mr. T. 
Iredale, who kindly examined the associated molluscs, states that they are distinctly 
of shallow water facies, and probably from not more than 50 fathoms in depth. The ~ 
specimens had been rotting for a fortnight before they were obtained by the Dominion 
Museum. 
The shell is large, pale horn-coloured to white, and broadly ovate in shape with a 
blunt beak and a slightly truncate but gently rounded front. The hinge line is 
moderately broad and strongly angled at the dorsal umbo. The convexity is considerable, 
the greater share being assumed by the ventral valve. There is an obscure broad 
median fold in the dorsal valve, flattened on top anteriorly, and a corresponding very 
shallow anterior sinus in the ventral valve giving rise to a flattened dorsally directed 
arch in the anterior commissure. The beak is short, sub-erect, with blunt beak ridges 
and a large epithyrid foramen which is labiate with a well developed pedicle collar 
within, The pseudodeltidium is not entirely concealed by the labiate foramen, and is 
of one piece, rather low, moderately broad and concave dorsally, The umbo of the dorsal 
valve is considerably incurved, and is hidden by the pseudodeltidium. ‘The surface of 
the shell show numerous fairly strong growth lines, and a very fine wavy radial striation, 
only clearly visible in a favourable light by the aid of a lens, but occasionally distin- 
guishable by the naked eye. The dimensions of the specimen chosen as holotype, are— 
Length 47 mm., breadth 42 mm., thickness 29 mm. 
The loop is short, extending forward little more than one-quarter the length of 
the dorsal valve. The crural bases are relatively long and project above the narrow 
hinge plates for nearly their whole length, being inclined slightly towards one another. 
The crural processes occur at the anterior ends of the hinge plates, and are long and 
pointed. The remainder of the primary lamelle are very short. The transverse band 
is of only moderate length with a ribbon narrow at the points of origin and in the middle, 
but swelling out anteriorly on each side. It is strongly arched ventrally, the top of 
the arch being flattened for a short distance. The cardinal process is moderately 
developed, but appears prominent owing to the incurving of the dorsal umbo. The 
thread-like posterior dorsal septum is clearly marked, but does not show through the 
shell, which is moderately thick, and not markedly grooved internally for the reception 
of the pallial sinuses. 
The sinuses of the mantle are narrow and not conspicuous in the dried shell. 
They send out many branches on each side alternately, and bifurcate repeatedly near 
the front margin, the branches uniting near the margin with those of the adjoming 
sinuses. Spicules are present both in the sinuses and in the branches. The body walls 
are braced with large interlocking spicules, which are more massive in the dorsal than 
the ventral portion; those of the dorsal body wall consist in the middle of large plates 
with dorso-ventral elongation of their rays and with few ‘‘ windows,” passing out on 
