FEBRUARY 1, 1901.] 
has already described on the basis of their 
external characters, and which Wieland is 
now engaged in studying from the stand- 
point of their internal structure; but also 
from the very noteworthy observations of 
Weber and Hirase respecting the occur- 
rence of motile spermatozoids in Zamia and 
Ginkgo. Our knowledge of the North 
American Cycads adds nothing as yet to 
the phylogeny of these plants as determined 
by European investigators, but the progress 
of the studies of the Yale material will be 
watched with the greatest interest, in the 
hope that they may yield facts of im- 
portance in this connection. In the mean- 
time, however, the deep significance of con- 
--elusions derived from the study of Euro- 
_pean material justifies a brief reference to 
the position of our present knowledge of 
_ this group of plants, which may be said to 
have commenced with a recognition of the 
similar characteristics possessed by a small 
group represented by Noeggerathia, Medul- 
losa, ete., characters which pointed both to 
a filicinean and cycadean connection, but 
which were too poorly defined to permit the 
assignment of the representatives to any 
specific position. A recognition of the iden- 
tity of Medullosa and Myeloxylon as sug- 
gested by Solms-Laubach and later con- 
firmed by Schenck and Weber, served to, 
prepare the way for a clearer conception of 
the relations existing between the indi- 
vidual members as also with other groups, 
and this gained final expression in Potonié’s 
determination that Noeggerathia, Medul- 
losa, Lyginodendron, Heterangium, Clad- 
oxylon and Protopitys represent a distinct 
group of plants having an affinity with the 
ferns on the one hand, and with the cycads 
on the other, thereby becoming of ordinal 
value. He therefore established the name 
Cycadofilices as a proper recognition of the 
important position occupied by them. An 
additional contribution to our knowledge 
of this exceptionally interesting group of 
SCIENCE. 
175 
plants has been given by D. H. Scott in a 
study of Medullosa anglica, which he shows 
to have a probable filicinean connection 
through the Heterangium type. He further 
concludes that while the Medulloseae are to 
be considered as having affinities with the 
Cycadaceae in a broad sense, they really 
constitute a short, divergent branch of the 
phylogenetic tree. 
The ancestry of the Coniferz has excited 
an interest almost as profound as that cen- 
tering in the Cycads, and although we are 
enabled to trace these plants more or less 
fully back to Silurian time, we are as yet 
unable to establish their relation to an in- 
ferior group, as in the case of the Cycads. 
Our present knowledge of the descent of 
the Coniferz rests chiefly upon a recogni- 
tion of that line of ancestry which passes 
through Cordaites and culminates in the 
Araucarian type. This has been gained by 
a careful study of the structure of the wood, 
as also of the foliage, inflorescence and fruit, 
as obtained from numerous European local- 
ities, notably those in France. Extensive 
collections of North American Cordaite are 
represented by the wood and foliage only, 
and though their value for phylogenetic 
purposes is thereby relatively limited, they 
have nevertheless contributed important 
data derived from a study of the stem 
structure, and afford a striking illustration 
of the superior importance of those histo- 
logical methods first employed in such con- 
nection by Witham, the value of which was 
so strongly insisted upon by Brongniart. 
Apart from the general evidence derived 
from this material, which points with great 
force to the development of the Araucarian 
type, the structure of the stem is frequently 
preserved with such perfection as to permit 
recognition of important phases in the evo- 
lution of structural features. Aslongagoas 
1840, Don pointed out that in the tracheids 
of Cycas revoluta, scalariform structure may 
occur at one end and bordered pits at 
