GrevillEj on New Diatoms. 
7 
prominent pseudo-nodules (elongated processes) ; 3 vein-like 
lines projecting from each side_, and the whole surface, except 
the angles, filled up with circular, remote, subequidistant 
cellules ; connecting zone filled with similar cellules arranged 
in oblique decussating lines. (Figs. 23, 24.) 
Hab. Dredged off Sydney, New South Wales, in 15 
fathoms. N. F. Dobree, Esq. 
This splendid Triceratium was detected by Mr. Norman in 
some material dredged by his friend Mr. N. F. Dobree, near 
Sydney. It is a very beautiful object, and fortunately, Mr. 
Norman obtained both front and side views of the frustule. 
The valve is very convex, and has three vein-like lines pro- 
jecting from each side, the middle one of which reaches half 
way to the centre. Remotely scattered over the surface are 
circular cellules, and at the angles are very prominent pseudo- 
nodules, — so called, but which in the front view turn out to 
be elongated processes; a circumstance which shows how 
difficult it is to describe these objects in the absence of per- 
fect materials. The front view is very interesting, as showing 
the processes referred to, terminating in a little obliquely 
placed disc so exquisitely dotted as to remind the observer of 
the compound eyes of insects. These punctate discs are the 
articulating surfaces ; and it is scarcely possible to resist the 
conclusion that some communication must exist between the 
processes of the frustules so united by means of this structure. 
Are they the base or scars of minute vessels intended to hold 
the chain of frustules together until the period of maturity and 
separation ? A little above, and on the inner side of the punctat 
spaces are terminal spines, the bases only being left in the 
specimens before me. In position they resemble those which 
I have observed in various other Triceratia, in some species 
of Entogoniaj and in the genus Hemiaulus. In the connect- 
ing zone of our present species, the round cellules are arranged 
symmetrically in oblique decussating lines. One specimen 
(fig. 24) exhibits a variation of structure intermediate between 
the connecting zone and the valve, consisting of a broad belt 
of totally different cellules, much larger, of a roundish-oval 
slightly quadrate shape, and closely arranged. How so re- 
markable an organisation should occur in one example and 
not in the others, is sufficiently perplexing. Distance between 
the angles of the valve -0060". 
Triceratium negledum, n. sp., Grev. — Valve with straight 
sides and subacute angles, with transverse lines cutting them 
off so as to leave a nearly equal hexagonal centre ; structure 
minutely punctate, in lines radiating from a small punctate 
