LOO The America ii Geologist. February, LSS4 
true title at ion are so different that we are forced to refer these Alga? to 
widely separated families. Geologists sometimes complain that bota- 
nists refuse definitely to name fossil plants whose impressions are left 
in sandstone, and, in the geological sense, well preserved ; but cases 
such as the present — and it is one out of a thousand — show how uncer- 
tain must be the determination even of the best stone printing of a fossil 
stem. What shall we say, then, of the positive settlement of the affini- 
ties arjd structure of fossil shadows, where there does not remain the 
faintest trace in stone of the entity that was and is not ?'" 
Brongniart also refers* to the great time range *of certain 
species described as Alga? under the name of Chondrites. They 
occur in vast numbers in the Flysch of Switzerland, the spe- 
cies passing by insensible gradations into each other. After 
giving a list of twelve species of the Algae, Brongniart says: 
"The remarkable points about this series of species are. that they 
have nothing in common either with the Alga? of the sub-Cretaceous 
epoch, nor with those of the Miocene; especially of Monte Bolca, with 
which this flora would be almost contemporaneous, according to many 
geologists ; and again, the identity of these species of Alga? in so many 
localities situated at great distances, localities so numerous for most of 
these species that I have not been able to cite them. M. Kurr has also 
described and figured under the name of Ch.bollensis, a Fucus of the 
Lias, the very varied forms of which are almost identical with Ch. tar- 
gionii, ozqualis and difformis," all of which are given in the list re- 
ferred to. 
The type of so-called seaweeds variously known under the 
names of Spirophyton, Taonurus, Alectorurus, Zoophycos, Phy- 
sophycus and Cancellophycus presents an instance of the ex- 
cessive multiplication of genera for the simple reason that 
they occur at different geological horizons. For example. 
Alectorurus is supposed to characterize the Silurian; Physo- 
phycus the Carboniferous ; Spirophyton the Devonian: Can- 
cellophycus the Jurassic ; Zoophycos and Taonurus the Cre- 
taceous or Eocene. Saporta when proposing the generic name 
Cancellophycus said : f 
"We replace by a new generic name those species of Zoophycos and 
Taonurus, applied, the one by Massalongo and Heer, and the other by 
Fiseher-Ooster, to those Alga 1 represented by the type of Chum] rites 
scoparius of Thiolliere. Not only do these terms appear to us im- 
*Chronological exposition of the periods of vegetation and the differ- 
ent floras which have successively occupied the surface of the earth. 
Ann. and Mag. Nat. Hist., 2d ser., vol. vi, London, 1850, p. 353. Trans, 
by Arthur Henfrev from Ann.d. Sci. Nat. Botan., ser. 8, vol. xi, May and 
June, 1849. 
+Plantes Jurassiques. Pal.Francaise, 2d ser. Veg. Text, p. 127. 
