FOSSIL PLANTS, 



665 



our possession. Several Bimllar are also figured 

 in Lindley and Hutton's work from the same 

 locality, and are there designated trigonoearpum 

 noggeratMi. Palm leaves and stems are found 

 in great abundance, and in good preservation, in 

 the upper, secondary, and tertiary beds ; and in 

 the island of Sheppey, immense numbers of 

 palm fruits and others of tropical climates are 

 found associated with marine shells and fragments 

 of various woods. Fig. J is a cone bearing a 

 close analogy to that of the Scotch fir, only 

 smaller, and found in the oolite. Figs, e e and 

 h Ti, are also fruits resembling those of the palm 

 tribe. 



Cycade^. There are only two existing genera 

 of this family, cycas and zamia, natives of South 

 America, India, China, and New Holland, where- 

 as five fossil genera have been discovered, con- 

 taining about thirty species. These occur chiefly 

 in the secondary strata of the lias, oolite, and 

 chalk, and occasionally, though more rarely, in 

 the tertiary series. These plants seem to have 

 been the chief materials whence the partial beds 

 of lignite or brown coal have been formed. Of 

 this description is the coal of Cleveland Moor- 

 land, near Whitby ; of Brora in Sutherlandshire; 

 of Buckeberg, near Minden, in Westphalia. 

 The Bovey coal and lignite of (Eningen are found 

 in the tertiary strata. The amber which is 

 found on the eastern shores of England, and on 

 the coasts of Prussia and Sicily, is supposed to 

 be a resinous exudation from the beds of lignite, 

 found in the tertiary strata. Fragments of fossil 

 gum were found near London, in digging the 

 tunnel through the London clay at Highgate. 



The cj'cadeffi form a beautiful family of 

 plants, and from their structure, assimilate in 

 many respects with palms, coniferje, and ferns. 

 The trunk of the cycadese has no true bark, 

 but is surrounded by a dense case, composed of 

 jjersistent scales, which have formed the bases 

 of fallen leaves ; these, together with other 

 abortive scales, constitute a compact covering 

 that supplants the place of bark. The leaves 

 rise around a single cone like the pine apple, and 

 are pinnatifid ; the fossil species appear to agi-ee 

 with the recent in the following particulars of 

 structure : 1. By the internal structure of the 

 trunk, containing a radiating circle or circles of 

 woody fibre, embedded in cellular tissue. 2. By 

 the structure of their outer case, composed of 

 persistent bases of petioles in place of a bai-k, 

 and by all the minute details in the internal 

 organization of each petiole. 3. By their mode 

 of increase, by buds protruding from germs in 

 the axills of the petioles. 



A number of silicified fossil trunks of cyca- 

 dese are found in the isle of Portland, immedi- 

 ately above the surface of the Portland stone, and 

 below the Purbeck stone. They are lodged in 

 the same beds of black mould in which they 



grew, and ai'e accompanied by prostrate tninka 

 of large coniferous trees converted into flint, and 

 by stumps of these trees standing erect with 

 their roots still fixed in their native soil.* 



/' 

 Frond of pterophyllum. 



This cut represents a portion of a frond, 

 either of a zamia or pterophyllum, found in the 

 lias beds at Cromarty, in the north of Scotland. 

 The structure of the leaflets, which are of tlie 

 same breadth throughout, would indicate its 

 belonging to the species pterophyllum. (See 

 p. 653). 



Fig. /, cut 238, represents a cone of the zamia, 

 as figured by Lindley and Hutton, from the 

 greensand formations of England. 



In a tertiary fresh water fonnation at QLnin • 

 gen. Professor Braun has enumerated thirty-six 

 species, chiefly dicotyledons, about two-thirds of 

 which belong to genera which still grow in that 

 neighbourhood, but their species differ and cor- 

 respond more nearly with those now existing in 

 North America, than with any other European 

 species. On the other hand, there are some ge- 

 nera wliich do not exist in the present flora of 

 Germany, and others not in Europe. Judging 

 from the proportions in which their remains 

 occur, poplars, willows, and maples, were the 

 predominating trees in the former flora of Qinin- 

 gen. Of two very abundant fossil species, one, 

 the populus latior, resembles the modern Cana- 

 dian poplar; the other the populus ovalis, re- 

 sembles the balsam popular of North America. 

 The determination of the species of fossil willows 

 is more difficult. One of these, the salix angus- 

 tifolia, may have resembled our present salix 

 viminalis. 



Of the genus acer, one species may be com- 

 pared with acer campestre, another with acer 

 pseudoplatanus ; but tlie most frequent species, 

 acer protensum, appears to correspond most 

 nearly with the acer dasycarpon of North Ame- 

 rica. To another species, related to acer negundo, 

 Mr Braun gives the name of acer trifoliatum. A 

 fossil species, liquidambar europeum, differs from 

 the existing 1. styi-acifluum of America, in hav- 

 ing the narrower lobes of its leaf terminated by 



* Biickland Cirol. Traiisact, 

 4 i' 



