ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
497 
( Pseudoraphidese ). (Nitzscliiacete, Cylindrothecaceae, Am- 
phipleuraceae, Surirellaceae, Diatomacese, Meridionacese, 
Trachyspheniaceae, Plagiogrammaceae, Licmophoraceae, 
Striatellaceae, Entopylaceae, Eunotiaceae.) 
II. Evolutio lateris valvaris centricus ita ut sculptura radialiter 
e puncto mediano oriens disposita sit (. Araphideae v. Crypto- 
raphideae.') 
A. Yalvae non orbiculari-rotundatae, sed 3-multi-angulataB v. 
elliptico-constrictae, saepe processus varios gerentes, zona 
seu facies connectivalis sculptura ab ea faciei valvaris 
diversa et analoga ornata. (Biddulphiaceae, Hemiauli- 
daceae, Isthmiaceae.) 
B. Yalvae orbiculari-rotundatae, nonnunquam processibus aciculis 
v. spinis instructae ; zona seu facies connectivalis plerumque 
exstria, subrectangularis v. nonnunquam undulato-constricta. 
(Melosiraceae, Xanthiopyxidaceae, Coscinodiscaceae, Eupo- 
discaceae, Heliopeltaceae, Asterolampraceae.) 
C. Yalvae turn aequales turn inaequales, imperfecte siliceae, cor- 
nubus spinis setisve instructae, zona connectivalis plus 
minus turgida, singula, breviter cylindracea. (Cheeto- 
ceraceae.) 
D. Yalvae conoideae v. acuminatae, saepius calyptra v. stylo 
terminatae, per laminas parce siliceas numerosas apparenter 
imbricatas striatas conjunctae. Frustula subinde per 
stylum calyptramve consociata. (Rhizosoleniaceae.) 
Pleurosigma angulatum.* — Dr. H. Yan Heurck describes a series 
of preparations of this diatom, accompanied by photograms, made with 
an objective of 2 • 5 mm. focal length and a numerical aperture 1 • 63. 
The alveolae or “ pearls ” exhibit themselves under the form of minute 
points, each surrounded by a crown of six secondary pearls, really interme- 
diate between the primary ones. A careful examination of the photograms 
shows that the cause of this appearance is that the alveolae are not really 
round, but hexagonal, the “ secondary pearls ” being the result of imper- 
fect focusing of the angles of the network. This view is confirmed by 
a comparison with the structure of Coscinodiscus excentricus. It is 
further shown that the valve of Pleurosigma consists of two layers, and 
that the alveolae are hollowed out in the substance of the valve. 
Fossil Diatoms of Japan, j — Prof. J. Brun and J. Tempere describe 
the numerous new and marine species of diatom found in the argilla- 
ceous calcareous deposits of Sendai and Yeddo ; the most noticeable 
peculiarity of which is that they have been fossilized not by silica but 
by calcium carbonate, which has filled all the valves in the crystalline 
state, accompanied by small crystals of black oxide of iron. 
)8. Schizomycetes. 
Structure of Bacteria and allied Organisms. :f — Prof. O. Biitschli 
deals with the finer structure of Bacteria in a monograph, the object of 
* Bull. Soc. Beige Microscopic, vi. (1890) pp. 10-2 (5 photograms). 
f Mem. Sci. l’hys. et Hist. Nat. Geneve, xxx. (1890) 75 pp. and 9 pis. 
i ‘ Ueb. den Bau d. Bacterien und vervvandter Organismen,’ 1890, 37 pp. 
(21 figs.). 
