ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 597 
Fossil Bryophytes.* — Sig. U. Brizi describes a number of fossil 
remains of Muscineae obtained from the neighbourhood of Rome. Of 
the twenty-five species described, twenty-three are existing forms, and of 
these eighteen still occur in the Roman Campagna. The remaining two 
are new species, belonging to the genera Bhynchostegium and Dicranum. 
A single species of Hepatic as was also found. 
Alg-ae. 
Formation and Erosion of Rocks by Algae. t — Prof. F. Cohn points 
out the important part played by very lowly organized Algae — Phyco- 
chromaceae and Cyanophyceae — in the formation of calcareous and 
siliceous rocks. Many beds of marble and travertin have been formed 
in this way. He further enumerates the algae that are known to destroy 
calcareous rocks by erosion. In all fixed algae there appears to be this 
contrast between the basal cells and the rest of the filament ; that the 
former excrete an acid which dissolves lime ; while the latter has the 
power of depositing a soluble lime-salt between the filaments, but within 
the mucilage which is excreted from the sheath. 
Classification of the Lower Green Algae. £ — Prof. R. Chodat and 
Dr. J. Huber place at the base of algae the genera Palmella and Tetra- 
spora , characterized by the palmelloid mode of division, i. e. in one 
plane only, no firm membrane being formed round the new protoplasts, 
which are separated from one another only by a mucilaginous lamella. 
Each cell thus formed may become transformed into a biciliated zoospore 
(megazoospore). 
From the Palmellaceae are probably derived directly the Volvocineae, 
in which the motile phase preponderates ; the simplest form, Chlamydo- 
monas , may be regarded as a megazoospore furnished with a membrane. 
Nearly allied to the Volvocineae are the Pediastrese, Pediastrum being 
comparable to a Pandorina in which the gelatinous mass has solidified 
round the products of division. 
Another group is constituted of the Pleurococcoidese, — unicellular 
algae in which the preponderating mode of multiplication is the sporan- 
gial, i. e. one in which each new protoplast is surrounded by a firm 
membrane. These develope further in several series. In the Chara- 
ciaceae the cell is isolated and fixed, and produces two kinds of zoospore 
which germinate at a distance from the parent plant. In Sciadium the 
zoospores are arranged in a rosette at the apex of the capsule. Ophio- 
cytium , Baphidium, Actidesmium , Mischococcus, Oocardium , and Dactylo- 
coccus are nearly related. 
A good example of the distinction between the palmelloid and the 
protococcoid mode of division is afforded by Tetraspora on the one hand 
and Monostroma on the other hand. From the latter genus are derived 
the Ulvacem. At the base of the Pleurococcoidem, which have hitherto 
been united under the name of Confervoideae, are the Chlorospha3reaceae, 
in which are two modes of multiplication, a vegetative septation and a 
sporangial division. This latter mode of division gives rise to the 
* Bull. Soc. Bot. I tal., 1893, pp. 369-73. 
t JB. Schles. Ges. Yaterl. Cultur, 1892 (1893) 2 te Abtheil., pp. 77-9; and 1893 
(1891) pp. 19-22. I Arch. Sci. Pliys. et Nat., xxxi. (1894) pp. 395-401. 
