FLORA OF LIGNITES. 163 



down to the present time, differs so greatly from our water-lilies 

 that Caspary, of Konigsberg, has formed for it a distinct genus 

 (Holopleurd)*. These seeds are oval, brown, and 2J to 3 milli- 

 metres (or -098 to '118 inch) in length; at one end (fig. 348, a, c) 

 they are furnished with a little circular operculum, which bears 

 a semilunar umbilicus and a small tubercle (fig. 348, d). The 

 seed-coat is very thick (fig. 348, b) ; and its superficial layer of 

 cells have sinuous walls. The seeds are of the size and form of 

 those of the common white water-lily, but differ from them in the 

 solidity of the seed-coat and the presence of the operculum ; in 

 these respects they rather approach the seeds of the Victoria 

 regia, Lindl., in which, however, the cell-walls are much less 

 thickened. 



The Cryptogamia are chiefly represented in the lignites by the 

 mossesf, whicli in some places occur in great quantities, and 

 form dense felted masses. The bog-mosses (species of Sphag- 

 num) , which are now so plentiful in turbaries, have one spe- 

 cies (Sphagnum cymbifolium) at Diirnten. Three species of 

 feather-mosses have been found at Diirnten, the most abundant 

 of which (Hypnum lignitorum, S chimp.) stands between Hypnum 

 palustre and H. ochraceum, which grow in mountain-brooks upon 

 stones and rotten wood. A second and abundant species (H. 

 priscum, Schimp.) is very like the Hypnum sarmentosum, Wahlb., 

 which grows in Lapland and on the loftiest summits of the 

 Sudettes; and the third species represents H. stramineum and 

 H. trifarium, which live in peat-bogs and forest-streams. From 

 Morschweil a species (Thuidium antiquum, Schimp.) has been 

 obtained, very like one (T. delicatulum] which now lives in 

 forests. 



* Prof. Caspary, of Konigsberg, has founded this genus upon, seeds found 

 in the lignites of Dornheirn and Wolfersheim, in the Wetterau. Prof. Heer 

 sent him specimens from Diirnten which he considered to agree with these. 

 They are identical not only in external form, but also in the structure of their 

 cells. These, when macerated, acquire a fine blue colour with sulphuric 

 acid and iodine, showing that the cellulose has been well preserved notwith- 

 standing the many thousands of years during which the seeds have lain in 

 the earth. 



t Prof. P. Schimper, of Strasburg, whose knowledge of mosses is most 

 profound, had the kindness to examine and determine these specimens. 



M 2 



