280 cu^.^iori. 



and more elevated portions of the old red sandstone, was main« 

 tained through all the subsequent epochs to the most recent 

 chalk formations ; amid the peculiar characteristics exhibited 

 in the vejretable forms contained in the coal measures, there 

 is, however, a strikingly-marked prevalence of the same fami- 

 lies, if not of the same species,^ in all parts of the earth as it 

 then existed, as in New Holland, Canada, Greenland, and 

 Melville Island. 



The vegetation of the primitive period exhibits forms v/hich, 

 from their simultaneous affinity w^ith several families of the 

 present world, testify that many intermediate links must have 

 become extinct in the scale of organic development. Thus, 

 for example, to mention only two instances, we would notice 

 the Lepidodendra, which, according to Lindley, occupy a place 

 between the Coniferse and the Lycopodiaceee,! and the Arau- 

 carise and pines, which exhibit some peculiarities in the union 

 of their vascular bundles. Even if we limit our consideration 

 to the present world alone, we must regard as highly import- 

 ant the discovery of Cycadese and Conifera3 side by side with 

 SagenariaB and Lepidodendra in the ancient coal measures. 

 The Coniferee are not only allied to Cupuliferaj and Betuliuce, 

 with which we find them associated in lignite formations, but 

 also with Lycopodiacese. The family of the sago-like Cyca- 

 dese approaches most nearly to palms in its external appear- 

 ance, while these plants are specially allied to Conifers in re- 

 spect to the structure of their blossoms and seed.J Where 

 many beds of coal are superposed over one another, the fami- 

 lies and species are not always blended, being most frequently 

 grouped together in separate genera ; Lycopodiacese and cer- 

 tain ferns being alone found in one bed, and Stigmariae and 

 Sigillarise in another. In order to give some idea of the lux- 

 uriance of the vegetation of the primitive world, and of the 

 immense masses of vegetable matter which was doubtlessly 

 accumulated in currents and converted in a moist condition 

 into coal,§ I would instance the Saarbriicker coal measures, 



* Adolphe Brongniart, Prodrome d'vne Hist, des VegUaux Fossiles, p. 

 179 ; Buckland, Geology, p. 479; Eudlicher and Unger, Grundzuge der 

 Boianik, 1843, s. 455. 



t " By means of Lepidodeudron, a better passage is established from 

 flowering to flowerless plants than by either Equisetum or Cycas, or 

 any other known genus." — Lindley and Hiitton, Fossil Flora, vol. ii., 

 p. 53. 



X Kunth, Anordnnng der Pflanzenfamilien, in his Handb. der Bof.anik 

 8. 307 und 314. 



§ That coal has not been formed froui veii('tM])]r! ii!)es clianed bv 



