8 
Greville_, on New Diatoms. 
umbilicus ; but, within tbe angle, passing in right lines from 
the transverse line. (Fig. 20.) 
Hab. Barbadoes deposit, Cambridge estate ; C. Johnson, 
Esq. 
I am not aware of any species with which the present 
diatom can be compared. There is no appearance of a pseudo- 
nodule. The transverse line which cuts off the angle is not 
like a rib, but appears rather like a break in the conti- 
nuity of the radiating lines of puncta, or like a groove, for 
there is a perceptible shadow. But there is not actually a 
break in the continuity of the lines referred to, but a sudden 
termination ; for the space between the transA^erse line and 
the angle is filled up with a different set of lines, arranged at 
a right angle to the transverse line. Distance between the 
angles -0025". 
Triceratium Kittomanum, n. sp., Grev. — Valve triradiate, 
the angles prolonged into narrow linear arms terminated by 
prominent pseudo-nodules; structure reticulato- cellulate, 
three rows of cellules being contained in the arms. (Fig. 18.) 
Hab. Deposit at Nottingham, Maryland, U.S ; F. 
Kitton, Esq. 
A very interesting species allied to T. Solenoceros and 
ligulatum, and, indeed, so similar in form, that any one, in the 
absence of minute examination, might be pardoned for pro- 
nouncing all three identical. Mr. Kitton, as I find from the 
drawings he has kindly permitted me to see, referred our 
present species to T. Solenoceros ; but the differences are in 
reality very decided. The last-named species has not the 
very slightest trace of a pseudo-nodule. In T. Kittonianum, on 
the contrary, it is conspicuous, and in the front view (accord- 
ing to Mr. Kitton^s drawing) projects above and below the 
connecting zone, like a hammer. The structure, also, is much 
more widely cellulate. Our new species, therefore, differs 
from T. Solenoceros both in structure and in being furnished 
with a pseudo-nodule ; and from T. ligulatum in structure. 
The front view of the pseudo-nodule in the latter has not 
been seen. The cellules of T. Kittonianum are hexagonal, 
and in the arms about 8 in -001'". Distance between the 
angles '0060'^ 
Triceratium nitescens, n. sp., Grev. — Small; valve triradiate, 
the arms linear-oblong, rounded at the ends, with 5 — 6 
short vein-like lines on each side, and minute puncta 
between the lines, the whole forming a marginal band, 
leaving a blank space down the middle ; centre with a 
few scattered puncta enclosing an irregular triangular space. 
(Fig. 19.) 
