L, Lesquereua on the Coal Formations of N. America. 71 
In this last section, three well characterized forms are peculiar 
to our coal-fields. The one has its surface stellately wrinkled 
around the scars; the second is wrinkled crosswise, and the third 
has double, oval, obliquely-placed scars united by a deep groove, 
and the surface is beautifully reticulated by narrow wrinkles, 
obliquely intersecting each other. The beautiful Sigillaria Schim- 
peri Lsqx., of which the large scars have nearly the form of an 
eye, is also a peculiar American form. e number of our spe- 
cies, as marked on the table, is too small. About ten new species 
belonging to the Geological State surveys of Kentucky, of Ar- 
kansas and of Illinois are not here counted. 
Syrigedendron Brgt.—The two species described by Mr. Brong- 
niart are common in America. I have never seen any other. 
Dr. Newbury indicates a peculiar species of ours under the 
name of S. Americanum Newb. 
Lepidodendron Sternb.—The great number of specimens of 
this genus collected from the base and the top of the millstone- 
grit series of our coal measures, has afforded a good opportunity 
for examining the development and variations of the scars at 
ently pretty large; but the difficulty of determining the species 
from specimens generally badly preserved has prevented or re- 
tarded the descriptions. - Knorria imbricata Sternb., is especially 
common below the millstone grit. 
_ Lepidophyllum Brgt.—We poet already seven well character- 
ied American species, and three new and unpublished ones. 
American types not related to any European species. 
isiecdus Brgt.—The number of cones of Lepidodendron is 
