44 The American Naturalist. (January, 
ferous teranes is more definitely fixed; and the identity or affinity of 
the floras with the others of the same age in lower latitudes is verified 
and found to constitute important evidence of climatic uniformity. 
In the strictly paleobotanic portion of the memoir, which is most 
useful to students of fossil plants, there are, besides the refiguration and 
redescription of many of Heer’s types, numerous points of special in- 
terest. To mention the many interesting species found, or the valuable 
specific correlations made by Dr. Nathorst, would far exceed the space 
available in a short notice. Among the more notable cases in the former 
class are the new provisional genus Pseudobornia, and the elaborations 
of the characters of Cyclostigma Haughton, which is here included in 
Bothrodendron, though a subgeneric differentiation is suggested. Pseu- 
dobornia appears, as its name indicates, to be Calamitic in its nature, 
though no prejudice is expressed as to its relations or possible identity 
with Bornia or Calamites. Pseudobornia ursina Nath. is very sugges- 
tive of Calamites inornatus Dn. The existence of a Knorrid stage in | 
Bothrodendron is made plain beyond doubt, while the absense of both _ 
Lepidodendron and Sigillaria in the Bear Island Ursa beds, gives rise : 
eee Ade a mg ioe wot A tir cB ES a S es 
to a strong presumption that the Stigmariæ found there are to be re- — 
ferred as roots to Bothrodendron, which Nathorst seems to think may 
have been the ancestor of Sigillaria and Lepidodendron. ; 
The flora of the Liefde Bay system of Spitzbergen with species of | 
Cyclopteris, Lepidodendron, Bothrodendron?, Psilophyton-like stems, — | 
and Psygmophyllum, while, indicating a Devonian age, is insufficient 
to warrant with confidence a closer correlation. A comparison, how- — | 
ever, of Nathorst’s figures shows a close relation of the Arctic Le ; l 
pidodendra with the American Upper Devonian species. It seemsto 
the writer that the Psygmophyllum williamsoni Nath., which isregarded 
by Nathorst as a Gymnosperm, deserves a comparison with our Archa- a 
opteris obtusa Lx., or the A. archetypus Schmalt. i 
The flora of the Lower Carboniferous of Spitzbergen with Sphenop- 
teris bifida L. and H., and other species (several of them new) of Sphen- 
opteris, Adiantites, Cardiopteris, Archæopteris, Lepidodendron, Halonia, 
Bothrodendron (B. tenerrimum A. and T.), Carpolithes, and Samarop- — 
sis, is closely related to, when not identical with, species in the Calici- — 
ferous Sandstone and Lower Carbonifi Limestone of Great Britain, 
or the Culum of continental Europe. Several of the species, €. g. 
Sphenopteris sturii Nath., S. flexibilis, S. kidstonii and Lepidodendron 
spitzbergensis are very close to, if not identical with plants found in the 
Pocono (Vespertine) series of the Alleghenies, or the Horton series of 
Nova Scotia, though the general aspect of the flora seems as a whole to 
be somewhat younger. 
