Editorial Comment. 321 
There are several striking features, which we will not here 
designate errors, to which attention may be specially di- 
rected: 
1. The Silurian, as a system, covers and includes the 
Cambrian, and the term Cambrian is reduced to the rank of 
such a term as Ordovician. 
2. Silurian as an epoch is made to include only what is 
usually known as Upper Silurian. 
3. The terms Upper Silurian and Lower Silurian are given 
as synonyms, the former of '"Silurian" and the latter of Or- 
dovician. 
4. The Taconic is placed above the Keweenawan. 
5. The Taconic is given as a synonym of the Lower Cam- 
brian, on the authority of Prof. Lapworth, who, according to 
the author, wished to substitute it in the scheme for the term 
Georgian. 
6. The Keweenawan is placed in the Huronian, that being 
the position in which the rocks it includes were placed by 
Logan and Murray when they first defined the Huronian. 
7. The whole space occupied by the above is about one- 
sixth of the space of the whole column of formations, which 
expresses a wrong idea of the relative time which they rep- 
resent in geological history ; it is probable that these terranes 
consumed, in their accumulation, as much time as all subse- 
quent geological time, and to them have been given as much 
study and as much literature as to all the later formations 
combined. 
8. The Arvonian and Dimetian are placed in the Lauren- 
tian, but the Pebidian is put in the Huronian; whereas, ac- 
cording to Sir Archibald Geikie, these are intrusives and be- 
long in the Lower Cambrian. 
It is evident to any geologist who is familiar with the geol- 
ogy of the Lower Cambrian and of the Archean, that this is 
a very inadequate and incorrect presentation. It is further 
evident that it is difficult, perhaps impossible, for any geolo- 
gist who has spent his time for several decades in the study 
of the stratigraphic distinctions of the Tertiary and of the 
Mesozoic, to fairly understand the magnitude of the earlier 
terranes, or to apprehend the great place they occupy in the 
history and the literature of the science. 
