GiiEviLLE^ on Neiv Diatoms. 
29 
In the absence of positwe evidence, it is liighly probable 
that this magnificent species occurs in guano from some 
part of the Peruvian coast, for in the slide of selected 
diatoms, in which two specimens are preserved, the other 
species are Anlacodiscus Comberi, A, scaber, and AuMscus 
Peruvianus. 
The centre is composed of a compact group of large 
cellules, from which radiate rows of smaller, more or less 
quadrate cellules, constituting a beautiful network. Many of 
the straight longitudinal lines of separation are thickened 
and opaque, as in ^. ornata, becoming attenuated as they 
approach the margin, and anastomosing with each other by 
terminating cross lines. The species differs from A. ornata 
in various points, but conspicuously in the arrangement of 
the dark lines of ornamentation. In that diatom there is 
a more or less defined circle at some distance from the centre, 
and the radiating lines invariably constitute four distinct 
groups, directed towards the respective angles of the valve. 
In A. radiata the radiating lines point equally in all 
directions, producing the effect of a sort of halo. 
AmpMtetras punctata, n. sp., Grev. — Lateral view, with 
concave margins and rather narrow, rounded angles ; surface 
covered with very minute puncta, which form converging 
lines towards each angle; marginal strife coarse, 20 in -001". 
Breadth between the angles -0024". (PL III, fig. 8.) 
Hab. Ceylon, very rare. Dr. Macrae. 
A pale species, with the margins somewhat folded, as in 
A, ornata, and causing the angles to a})pear narrower than 
they would otherwise be. A small cluster of puncta occupies 
the centre, and then a series of radiating lines of smaller 
puncta converge towards each angle, becoming more and 
more minute as they fill up the angle itself. The strise of 
the folded margins are strong and coarse. 
