Greville, on New Diatoms, 
91 
Hab. Barbadoes deposit^ Cambridge estate; C. Johnson, 
Esq. 
I am not aware of any species witb which our present 
diatom can be confounded. The radiating puncta are pale, 
slightly increasing in size from the centre to the margin, 
which latter is well characterised by a row of larger and 
darker roundish cellules, 8 in '001'", which become smaller 
by degrees and disappear before reaching the angles. 
Triceratium atteyiuatimij n. sp., Grev. — Small; valve with 
undulate sides and attenuated angles, terminating in short 
minute horns ; whole surface loosely cellular, with a circular 
umbilicus and a band of linear-oblong cellules cutting off 
each angle. Distance between the angles -0027"'. (Fig. 10.) 
Hab. Barbadoes deposit, Cambridge estate ; in slides com- 
municated by C. Johnson, Esq. 
A singular diatom, bearing no resemblance to any recorded 
species of the genus. The reticulation may be compared to 
a pattern of fine lace-work. The rather large umbilicus con- 
tains a few obscure cellules considerably larger than those of 
the general area, while those of the angles are smaller. The 
most remarkable feature is the row of about seven or eight 
linear-oblong cellules placed side by side, and which cut off 
the angles. 
Triceratium ligulatumy n. sp., Grev. — Valve triradiate, the 
segments somewhat ligulate, terminated by a sub-elliptical, 
obtuse pseudo-nodule ; surface fitted with minute, radiating 
puncta. Distance between the angles -0038''. (Fig. 9.) 
Hab. Barbadoes deposit, Cambridge estate ; in slides com- 
municated by C. Johnson, Esq. 
This species is nearly allied to T. SolenoceroSj but is sepa- 
rated from it by the pseudo-nodules, which are cut ^ofi* by a 
fine transverse line, and are very minutely punctate. There 
is also a row of marginal puncta, larger and darker than 
those which radiate from the centre. 
Triceratium incequalCj n. sp., Grev. — Minute; valve un- 
equally triradiate, the angles minutely obtuse, the extreme 
ends separated by a transverse line ; surface minutely and 
faintly punctate, the margin composed of a line of close, 
larger puncta. Distance between the angles '0020"' to 'OOSO^'. 
(Kg. 19.) 
Hab. Barbadoes deposit, Cambridge estate; in slides 
communicated by C. Johnson, Esq. 
Invariably with unequal sides, so that one arm, at least, 
is extended more than the others. The sides are unequally 
concave; the angles prolonged and slender. There is no 
