70 
Greville, on New Diatoms. 
angles produced, capitate ; centre divided into compartments 
by radiating, vein-like veins. Distance between the angles 
•0027". (Fig. 9.) 
Hah. Barbadoes deposit ; excessively rare. 
This beautiful species is evidently related to T. truncatum 
and T, venosum ; to the former very closely, while, at the 
same time, it is abundantly distinct ; the truly capitate, pro- 
duced angles taking the place of the broad, truncate angles 
of that diatom. 
Triceratium inconspicuum, n. sp., Grev. — Minute, sparsely 
punctate ; angles of the , valve semicircular, subtruncate, 
separated from the centre by a transverse line ; centre 
bordered with a row of puncta. Distance between the angles 
•0005". (Fig. 10.) 
Hab. Barbadoes deposit ; excessively rare. 
Of this exceedingly minute species I have seen half a 
dozen specimens, all of which have four angles. In its cha- 
racters it comes very near to some varieties of T. hrachiatum, 
but is separated by its size alone, which scarcely exceeds 
that of T. exiguum. 
Triceratium delicatum, n. sp., Grev. — Minute ; valve with 
slightly concave sides and broadly rounded angles filled up 
with transverse rows of fine puncta ; centre containing a 
pale, obtusely triangular band, within which is a triangular 
spot, bordered with puncta. Distance between the angles 
•0012''. (Fig. 11.) 
Hab, Barbadoes deposit ; excessively rare. 
A minute species, difficult to define in few words. The eye 
is first impressed with the pale (blank), triangular band, 
which exactly fills up the centre of the valve by the angles 
reaching to the concave margin, and, consequently, separating 
the angles of the valve from the parts within. In the central 
spot, which is edged with a row of distinct puncta, I have 
been unable to trace any particular structure. A peculiar 
feature in this little diatom is a considerable space between 
the sides of the pale band and the transverse rows of puncta 
which occupy the angles. These puncta also gradually de- 
crease in size as they approach the apex. 
Triceratium labyrinthaumy n. sp., Grev. — Valve with 
rounded angles and somewhat convex sides, the centre 
having a network of flexuose, widely anastomosing, vein-like 
lines, the inclosed spaces being finely punctate. Distance 
between the angles -0023". (Fig. 12.) 
Hab. Barbadoes deposit ; excessively rare. 
Of all the curious Triceratia which have been discovered 
in this inexhaustible deposit the present species is one of the 
