28 Greville^ on New Biatoiita. 
figures, are dissimilar, and the remarkable bristle which 
accompanies each pseudo-nodule in Mr. BrightwelPs speci- 
mens serves still more decidedly to separate them. Mr. 
Ealfs, in his remarks under T. orhiculatuni Pritch. Inf./ 
1861^ p. 853), is evidently under the same impression. I 
beg to suggest that while the original name be retained for 
Mr. Shadbolt^s species, the other may be named T. Shad- 
holtianum, Mr. Brightwell having a species already dedicated 
to him. The following characters will serve to distinguish 
them : 
T. orhiculatam, Shadb. — Valve with very convex sides, 
obtuse angles, and conspicuous pseudo-nodules; cellula- 
tion minute, decreasing in size from the centre to the 
margin. (Shadbolt, ' Mic. Trans.,'' vol. ii, p. 15, pi. i, fig. 6.) 
T. SJiadboltianura, Grev. — Valve witli nearly straight sides 
and obtuse angles, each with a prominent, circular pseudo- 
nodule, accompanied by a spine ; puncta minute, radiating, 
T. orh'iculatmn, Brightw. — "^Mic. Journ.,^ vol. iv, pi. xvii, 
fig. 20. Ralfs (^Pritch. Inf.,' 1861, p. 853), in part. 
Tricerat'mm Thivaitesianum, n. sp., Grev. — Large, valve 
with straight sides, rounded angles, and rather large pseudo- 
nodules ; surface filled with large, irregularly hexagonal 
cellules, about 5 in '001", commencing, but not radiating, 
from the centre, and becoming smaller towards the angles, 
where they suddenly pass into inconspicuous puncta. Dis- 
tance between the angles '0050". (PI. Ill, fig. 5.) 
Hah. Cape of Good Hope, Dr. Macrae. 
An exceedingly distinct species, not so regular in its 
reticulation as T.favus and its allies, and peculiar in having 
the centre indicated by the arrangement of the cellules, not 
very evident to a careless observer, but quite distinct when 
the eye is directed towards it. The central cellules are very 
sliglitijr elongated, but there is no distinct radiation. The 
angles appear to be produced into large, conical processes ; I 
have not, however, seen the front view. 
Amphitetuas. 
Anipliitetras radiatu, n. sp., Grev. — Valve Avith slightl}' 
concave sides and broadly rounded angles ; the centre com- 
posed of a nucleus of large cellules, the rest of the surface 
covered with a network of radiating quadrate cellules, and a 
circle of dark, radiating, thickened lines anastomosing and 
terminating near the margin. Diameter '0058". (PI. Ill, 
%• 7.) 
Hab. Peruvian (?) guano, Dr. Macrae. 
