44 UNITED STATES GEOLOGICAL SURVEY— TERTIARY FLORA. 



we do not find in the lignite coal any identifiable remains of the plants. It is 

 only when these hard species of Mosses are casually deposited in mud or 

 clay, or buried into sand-banks, that their forms are preserved for an indefi- 

 nite length of time. The species described below appear to have been 

 imbedded in that way along the muddy borders of a shallow lake. Of the 

 European fossil species, all those referable to the division of the Acrocnrpl 

 have been found in the Succin by Goeppert ; the others, all Pleurocarpi, 

 especially referable to the genus Hypmnn, have been discovered in layers of 

 clay or in beds of sandy shale. 



HYPmJM, linn. 



II y p 11 II ni - H a y d e n i I, Lesqz 



Plate V, Figs. 14-14 b. 



Bypnum Haydenii, Lesqx.) Anunal Report, 1874, p. 309. 



Stem rigid, sparingly divided in nearly opposite, snbalternate, short branches, slightly inflated 

 toward the top, or club-shaped ; leaves closely imbricated all axoaud the stem and branches, ovate- 

 lanceolate, acuminate, concave. 



The specimen is figured as far as it is discernible. The fragment 

 resembles a branch of a coarse species of Hijpnum, like H. rugosum, H. Boscii, 

 especially, a species which has its largest branches divided as in this fo.ssil 

 Moss, and of equal size. The mode of division of this plant separates it from 

 the Lycopods, while the apparently thick leaves seem abnormal for a species 

 of Moss. It is well to remark, however, that the matrix wherein the fragment 

 is preserved is a hardened plastic clay, of very fine texture, where even deli- 

 cate small feathers, wings of insects, etc., are distinctly recognized, and that, 

 therefore, the form of the leaves of a hard species of Moss, even their convexity, 

 may have been easily impressed upon that kind of soft substance. No trace 

 of middle vein is visible, of course, for the species of Hypnum have rarely 

 the nerve prominent enough upon the back of the leaves to leave an impression 

 by compression and fossilization. The point is very acute and apparently 

 piliferous, but this last character is not positively ascertained. 



Habitat. — South Park, Colorado, near Castello's Ranch {Dr. F. V. 



Hay den). 



LYCOPODIACE^. 



Species of this family represent an important part of the vegetation of the 

 old coal-measures, not only by large trees, Lppidodendron, Ulodendron, and other 

 allied genera, but by true species oi Selagimlla and Lycopodium, known by their 



