BRACH10P0DA—THOMSON. 17 
The shell is broadly ovate with rounded sides passing gradually into a rounded 
front. The greatest breadth is a little in front of the middle. The hinge line is of 
moderate breadth and obtusely angled. The convexity, in which the ventral valve 
assumes a slightly larger share, is only moderate. There is a slight tendency to dorsal 
uniplication, revealed chiefly by the arching of the anterior commissure, but also by a 
slight flattening towards the sides of the dorsal valve. The beak is rather short, sub- 
erect, without pronounced beak ridges, and is truncated by a fairly large epithyrid 
foramen, which is marginate with a well developed pedicle collar within. The growth 
lines are not well marked, and there is an almost obsolete faint radial striation only to 
be discerned with a magnifying lens. 
In the dorsal valve the septum is not conspicuous, but may be clearly seen by 
holding the shell up against a strong light. The loop is short, extending forward only 
two-sevenths the length of the valve. The transverse band is relatively broad and 
presents two folds directed ventrally with a groove between them. The crural bases 
are longer than the sides of the loop, and the crural processes occur right at the end of 
the hinge plates. The crural bases diverge rather rapidly and are raised above (ven¬ 
trally of) the hinge plates anteriorly and gradually descend to their level about halfway 
to the umbo. The hinge plates are concave ventrally. The cardinal process is low and 
very broad. 
No spicules were observed in the sinuses of the mantle, or in the cirri, and they 
occur only sporadically in the body walls. In the arms they are well developed, con¬ 
sisting of a row of massive stellate main plates on both dorsal and ventral sides of the 
arms, and a row of pyramidal cirri socles at the base of the cirri on the dorsal side only. 
Both rows of plates vary considerably from place to place, the cirri socles in places 
losing their pyramidal shape by the development of a large spine in place of the base of 
the pyramid, and take the appearance of a cross. The main plates are roughly stellate 
with a small central disc, which is occasionally perforated by small “ windows,” while 
the rays have a tendency to bifurcate. The lateral branches in both series overlap 
one another. The general shape and the relationships of both rows of spicules agree 
with those described for L. cintarctica by Eichler, though not so well in the shape of 
the main plates with the figure given by Blochmann. In a young specimen of 6 mm. 
the cirri socles continue from the dorsal side right to the proximal end of the ventral 
side of the side arms, be., somewhat further than in the cases studied by Eichler. 
The discovery of this species off Adelie Land represents a considerable extension 
of its range, the previous specimens being all obtained from the Winter Station of the 
“ Gauss ” in 385 metres depth (210 fathoms). 
Liothyrella neozelanica sp. nov. 
(Plate XVI, figs. 36, 37, 38; plate XVII, figs. 51, 52;. plate XVIII, figs. 61, 62, 64.) 
Habitat .—On a flat stone entangled on a fishing line of 200 fathoms length, Cook 
Strait, off Wellington, New Zealand. 
*20218—C Vol. IV, Part 3. 
