and Species of Diatoms from the South Pacific. 37 
gramma), but is far removed in structure by its vitte and 
central nodule. 
Omphalopsis australis, n. sp., Grev.—(Figs. 10, 11). 
Hab. Woodlark Island ; in a dredging communicated by 
Dr Roberts. Not unfrequent. 
Frustules varying considerably in size, but generally 
about 0022" in length, rectangular, the angles slightly 
rounded, and the striz forming a very narrow marginal 
border; valve cruciform, about ‘0012” in breadth in the 
middle; nodule large, prominent, circular; strie 11 in 
001", strong, submoniliform, somewhat oblique, radiating 
in the centre, where a short one usually occurs at the outer 
margin, interrupted, leaving a narrow blank median space 
which terminates at the vittee which cut off the rounded 
ends. At first sight, the large boss-like nodule and robust 
strie convey an impression that the valve may belong to 
a species of Glyphodesmis, but, as already remarked, the 
terminal vitte and different structure essentially separate it. 
AMPHITETRAS, 
Amphitetras parvula, n. sp., Grev.— Lateral view with the 
sides slightly convex, the angles rounded, containing a large 
pseudo-opening ; centre marked by two cruciform lines of 
cellules which intersect each other in the middle and give 
off radiating lines of minute puncta. Breadth between the 
opposite angles ‘0015” (fig. 12). 
Hab.—New Caledonia; in a dredging communicated by 
Dr Roberts. Very rare. 
_ Frustule very small, quadrangular, the sides very slightly 
convex, the rounded angles being formed by the pseudo- 
openings which are very conspicuous, the true margin, con- 
tinued on the inner side of the openings, strong and dark, 
outside of which the edge of the connecting zone appears 
constituting a secondary margin, which passes to the apices 
of the pseudo-openings. ‘The internal space is equally 
divided by two lines crossing in the middle, composed of 
two contiguous rows of cellules, which are mostly visible in 
consequence of the shadow they produce, while from each 
side of these rows pass inclined lines of very minute puncta. 
