26o (Review of decent Geological Literature. 
nepheline rocks, whether felsitic, as phonolyte, or granitic, as fojayte, 
and (4) the probable Palaeozoic age of the whole eruptive series. 
The Geological Magazine for February. In the February number of the 
Geological Magazine Sir. Wm. Dawson notes several new facts regarding 
Eozoon. He says that some recently found specimens show that it had 
a definite form which was funnel, or top-shaped ; that it had no theca above 
or below, and that the lamin.e coalesce at the margin. These laminae 
are thickest at the base and become thinner and confused above. Sir 
Wm. Dawson is convinced that the forms which he described under the 
name of Archteosphaerinae are only these upper layers of Eozoon. 
Some cut specimens of Eozoon show, he states, a tubular structure to 
which he applies the term "oscula" apparently suggested by some re- 
semblance to the "oscula" of sponges. He also draws attention to the 
fact that some of the Laurentian limestones contain abundant frag- 
ments of Eozoon, showing its peculiar granulated structure, but not its 
canals. 
Sir William then suggests that certain bodies found in the Lauren- 
tian of the Ottawa district, and the Cryptozodn of Hall and Winchell from 
New York and Minnesota, may be related to the Eozoon of the Lauren- 
tian limestones. 
In conclusion he urges, against the views of Mr. Julian and others, 
who maintain the mineral nature of Eozoon, the following objections. 
1. Laminated minerals have simple laminae; those of Eozoon are con- 
nected. 
2. Laminated minerals are wholly crystalline; Eozoon has tubercles 
and "oscula." 
3. Is it probable that pyroxene, serpentine, loganite, dolomite and 
earthy limestone should all assume the same form.^ 
4. Eozoon often occurs away from the nodules and bands of pyrox- 
ene, etc., in the limestone. 
5. Eozoon does not resemble any banded rocks known in the Lauren- 
tian series. 
Prof. Bonney contributes the results of some experiments, and observa. 
tions on the rounding of pebbles by rivers and streams chiefly in the 
Alps. The process is of course most rapid when the motion is swiftest, 
that is in the higher parts of their courses. He lays down the following 
principles which are fully in accord with Daubrde's previous conclu- 
sions: 
I. The time of rounding a stone depends upon its nature. 
I. Stones are rounded most quickly where the descent is rapid and 
but slowly when the stream is only just able to move them. 
3. The process is most rapid at first. "Perhaps we may venture to say 
as a rough standard of comparison that the effect of a thousand feet of 
rapid descent is equivalent to that of the more leisurely traverse of at 
least twent}' miles, so that fairly well rounded pebbles of a rock with 
hardness not exceeding 6 signify either a rapid descent of 3,000 feet or a 
journey at less speed of 60 miles." 
