SURFACE DIATOMACEZ FROM HONG-KONG HARBOUR. 49 
In Pritchard’s Jnfusorva, and other text-books on Dia- 
tomacee, three distinct species of B. are described, viz. :—JB. 
furcatum, B. curvatum, and £. nodulosum; but from the 
foregoing description of structure, it will be seen that they 
are merely different parts of a perfect filament of one 
and the same species. 
B. nodulosum is a terminal cell with the spirally-arranged 
beads strongly marked. 
The awns of the Kong-Kong species are always spirally 
beaded, this being most evident in the terminal cells ; while 
in the bifureated awns of the intermediate cells the beading 
is only evident on the free extremities. 
The sporangial endocysts (fig. 12) of this genus are 
smooth on the larger curvature, with a few delicate spines 
on the smaller end. 
Figs. 13 and 14 represent a.curious diatom which is not 
uncommon in Chinese waters, and the classification of which 
is, I think, rather doubtful. It is very closely allied to Mr 
Wallich’s Hemidiscus cuneiformis, which he has placed in 
the family Anguliferex, and the detached frustule has been 
named by Mr Greville Palmeria Hardmaniana ; but, as 
far as I am aware, it has not hitherto been described as it 
appears in its living and perfect condition. 
Each frustule is similar in shape to the carpellary 
segment of an orange, and by the apposition of six or eight 
of them side by side, arranged as the segments of an orange, 
a globular compound plant is formed (fig. 14). It is probable 
that the spheroidal shape is only a phase in the growth of 
the plant, as its form must alter and tend to become annular 
as the frustules multiply ; it then probably breaks up into 
smaller groups of frustules, which form the basis of a new 
sphere. The frustules fall apart on very slight disturbance, 
and the perfect sphere is only seen when recently taken 
from the sea. 
The valves (fig. 13) are nearly flat, semilunate in outline, 
with a straight or very slightly concave venter ; the surface 
of the valve is minutely cellulate, the lines of cellulation 
radiating from a clear space in the centre, interspersed 
at regular intervals by more strongly marked radial lines, 
each of which has a minute spicule at its peripheral termi- 
