208 
- These divisions are seen very conspicuously in Actinocyelus and 
Actinopticlus.- In the large species of Coscinodiscus the number of 
sectors appeared to be twelve, from the groups of rows at the centre, 
and in it was shown the very beautiful arrangement of the cells in 
radiating and intersecting spiral lines. Eupodiscus Ralfsii was refer- 
red to as affording an example of the division of the circle into sec- 
tors, within which the lines of cells are arranged symmetrically on 
each side of a single radiating row, to which the rest are all parallel. © 
In Eupodiscus maculatus the disk is divided into ten; but the rows 
of cells do not converge towards the centre, except one at the side of 
each sector, to which the others are parallel. From this may be 
derived the very beautiful construction of the Coscinodiscus eccentri- 
cus, in which the disk is divided into seven sectors ; the rows of cells 
extending across the valve from each sector, to meet similar rows 
from the second sector beyond. 
Sections of Coal. 
‘On the various Sections of Coal, considered in their relation to the 
Block, and the relative views of Histologists thereon ;’ by Mr. Neil 
Stewart. 
The author stated :— 
“ Since last July I have frequently been employed in making draw- 
ings of sections of coal, as seen under the microscope by transmitted 
light, and have therefore been obliged to give this subject some 
attention. In the prosecution of this work I have felt great difficulty 
in bringing to my aid the willing zeal so necessary to the spirited 
delineation, and which can only be commanded in proportion to the 
knowledge which the artist has of his subject. ‘This I can only 
account for by stating, that a suspicion passed upon my mind, from 
the beginning, that something was wrong with regard to: sections; 
and this suspicion, which I frequently mentioned to gentlemen 
engaged in the investigation of this subject, increased with my know- 
ledge, until, on reading Mr. Quekett’s paper, in the ‘ Microscopical 
Journal’ for January last, I found that he there expresses a notion 
similar to mine, but immediately contradicts it by again returning to 
the usually received opinion. With a view, therefore, to satisfy my 
own doubts, and, if possible, to make a contribution to scientific truth, 
I have examined cubical blocks of various coals by direct light; and 
with my own hands have made sections from all the sides of these, 
and again‘examined them by transmitted light. I have also made 
drawings of such sections which are now before the Society. 
