RECENT RESEARCHES IN THE DIATOMACEA. 303 
-cell-wall, and which is most highly developed s the extremities, we have, 
in Brebissonia, "n central plasm-mass which occurs in all the mbellee 
and Naviculee. mass of thicker ge interposed between the endo- 
chrome-plate and the cell-wall, which is found in Frustudia, is present 
also in Brebissonia ; in the latter case, as in all the Cymdellee, only one of 
these occurs in each frustule, and this lies across the middle of one 
girdle-band. This structure in Bredissonia is large and calico the 
single endochrome- slats covers the same girdle-band, folding itself over 
the valves on both sides till its free edges nearly meet on the opposite 
plate into similar halves by an incision from the extremities throughout. 
runow gives no special characters e the genus Brebissonia, the 
detailed description of its peculiarities by Pützer is the more valuable, 
and exhibits the relationship of this interesting form more clearly than 
hitherto has bee 
- Anomoconeis. — The only form bins with  certainity can be assigned 
to this genus, iesprütik to our author, 1 ,us het inks, 
Nasicala spherophora, Küt tz. lt hears a Rie resemblan - to Navicula 
en; its VIN. however, are not furnis ed e transverse striz, but 
with fi uncta arranged in quineunx. On one side of the qp 
The tired space on one side of the valve which is characteristic 
of Axomoconeis, occurs = a similar manner in die sculpta, Ehren., 
and to slighter extent in . bohemica, net o that for this reason 
the author considers best Jatter-named M may be included in 
Anomoeoneis 
I have some doubt as to the identity of Anomoconeis splueropho ore, ™ 
Pfitzer, with qiiia spherophora, Kütz. The failure of the striation on 
one side of the central nodule, md extending thence to the margin of the 
valve, a feature so characteristic of 4 herophora, doe p 
Kätzing s oe o herophora, nor in that of Smith Donkin (Brit 
Diat g. 10) does not € this a ; it is not apparent in 
should have "üppoesd Pfitzer had Navicula telis fa view, wete it not 
hapa of this species, as well as that of B dini rage his o A 
tions on the unsymmetrical characters of the contents of ‘the frustrule 
