162 QUATERNARY PERIOD. 



They carniot be distinguished from the seeds of the living spe- 

 cies, which occurs in the pile-dwellings of Robenhausen. The 

 common reed is most abundant at Utznach and Diirnten in the 

 earthy dark-coloured intercalated bands (" silver"); these are 

 in places closely traversed by shining black bands, formed by 

 the jointed rhizomes and leaves of the reed, the latter marked 

 with numerous longitudinal lines. Sometimes the branches 

 and fibrils issuing from the knots of the rhizomes have been 

 preserved. Frequently these masses of reeds fill whole beds, to 

 the exclusion of all other plants; hence they probably formed 

 the whole of the sedgy growths where the peat was covered by 

 a clayey layer. 



Of the bulrush (Scirpus lacustris, Linn.), only the fruits 

 (fig. 346) have been preserved; but these are not uncommon 

 in the clay beds at Diirnten, and agree exactly with those of 

 the living plant, which has also reached Prof. Heer from the 

 pile-dwellings of Robenhausen. In the same clays at Diirnten 

 Prof. Heer found a few seeds of the raspberry (Rubus idaus, 

 Linn.), of the water-pepper (Polygonum hydropiper, Linn.?), 

 and of the water-chestnut (Trapa natans, Linn.?). The deter- 

 mination of the two species last mentioned, however, is not 

 quite certain. Of the Trapa Prof. Heer has found no entire 

 fruit, but only spiny fragments, which, however, suit this plant 

 very well. 



Of the white bedstraw (Galium palustre, Linn.) the fruits are 

 tolerably plentiful at Utznach and Diirnten ; they occur as little 

 spheres of the size of grains of powder, slightly wrinkled exter- 

 nally, and are scattered through the lignite-beds. A cranberry 

 ( Vacciniwn vitis idaa, Linn.) is known only by a single coria- 

 ceous leaf (fig. 347) collected at Diirnten. It is well preserved ; 

 but its determination is still doubtful. 



All these plants of the lignite still grow in Switzerland ; those 

 which occur in the lignites themselves grew on peat-bogs, whilst 

 the species found in the intercalated clays (namely the yew, the 

 hazel, the raspberry, and the water-nut) were swept down by 

 water from the neighbourhood and deposited with the soil carried 

 down at the same time. The only flowering plant which cannot 

 be referred to any existing species is a water-lily, which, in the 

 structure of its seeds, the only remains of it that have come 



