GrevillEj on Asterolamprcs. 
51 
sections_, whicli are entirely destitute of any punctate portion, 
represent the segments. A lively imagination might compare 
the umbilical lines to a set of cords made to draw the segments 
by main force towards the centre, pulling them out of their 
normal shape, and straining upon the cellules of their inner 
margin, until the whole mass was screwed up from a truncate 
to a conical outline. The eye naturally rests upon the lines 
in this disc , but if it be fixed upon the spaces, the effect is 
very beautiful. 
One of Ehrenberg^s perplexing genera, Cladogramma, the 
character of which is not, I believe, anywhere published, 
seems from his figure (copied into ^ Pritch. Infus.,^ pi. viii, 
fig. 11), as if it might possibly bear some relation to our 
present subject. But as the valve is said not to be cellulate, 
there can, of course, be no affinity. It is not, indeed, 
certain that Cladogramma belongs to the Diatomacece at all. 
VI. Inner margin of the segments either smooth, or not 
continuously punctuate. 
12. Asterolampra punctata, n. sp., Grev. — Segments 
truncate, containing somewhat distant, and more or less im- 
perfect, radiating rows of equal puncta j the lateral margins 
composed of similar puncta. Diameter about 'OOSO". (Fig. 32). 
Hah. Barbadoes deposit ; rare ; T. G. Rylands, De Bre- 
bisson, E. K. G. 
A curious species, constituting a transition from the present 
to the next section. It has the slender umbilical lines and lax 
central cellules of this section, while the segments are partially 
smooth ; and the puncta, instead of becoming more minute 
as they approach the external margin, are all of equal size, 
circular, and disposed in distant lines in the most irregular 
fashion imaginable. At the lateral margins, indeed, the row 
of punctation is complete ; but in the rest of each segment 
there are often not more than one or two complete rows. 
Sometimes a solitary punctum stands for a whole row ; 
sometimes two ; sometimes three ; and the deficiencies may 
occur in any part of the row. In this way the inner 
margin of the segment may be to a considerable extent 
smooth. The number of rays seems to average six or seven ; 
but the umbilical cellules vary in the specimens I have ex- 
amined — from five to nine — and have, probably, a still greater 
range. I have never seen them wanting. 
Asterolampra Icbvis, n. sp., Grev. — Small ; segments trun- 
cate, opake, smooth ; the inner margins slightly thickened ; 
rays short. Diameter -0015". (Fig. 33). 
Hab. Barbadoes deposit ; extremely rare. 
