L. Lesquerewx—Rocky Mountain Lngnitic Formation. 441 
was obtained with the Hyalonema, and also several other re- 
long, and the expanse of its tentacles was over six inches. 
color of its body was deep olive-brown. This species was not 
discovered until last year, but it was met with at several differ- 
ent localities this year, and seems to be not uncommon on 
muddy bottoms in 20 to 100 fathoms, though seldom obtained 
of full size by the dredge, owing to its living deeply buried. 
[To be continued. ] 
Art. L.—Age of the Rocky Mountain Coal or Lignitic Formation. 
mporta gy: e | ive first 
the conclusions of Mr, L. Lesquereux from the fossil Plants, pub- 
lished in Hayden’s Report for 1872.—Ebs. | 
Il. Views of L. Lesquereux. 
_ Not a single leaf has as yet been found in our Eocene iden- 
tical with a Cretaceous species. The genera especially repre- 
sented in the Cretaceous are: Sassafras, Creaneria, latanus, 
but from analogy I doubt if we may ascertain the presence 0 
any of these types even in our oldest floras. 
our Cretaceous, as more easily recognized by gah 
living species, leaves of Sassa/ras and of Liriodendron, the tulip- 
e. 
; : fusion of leaves of Sas- 
If 1 should judge By te E of the Dakota group, in 
tati i sist of species of this genus. pu 
on of this epoch did consi P to have lived in 
