46 G 



PAL.EOBOTAXY. 



West Indies, Japan, Australia, Southern Asia, and South 

 Africa. As has been already remarked, the occurrence of 

 genuine Cycads in the Carboniferous vegetation has not been 

 demonstrated, and the same holds good of all the Palaeozoic 

 floras. True Cycads, therefore, so far as known, make their 

 first appearance in the Trias, at the commencement of the 

 Mesozoic period, where they are represented by the genera 

 Pterophyllum, Zamites, and Podozainites. Cycads continue to 

 be abundantly represented throughout the whole ]\Iesozoic 

 series ; but they have only been detected by a single dubious 

 example in strata of Tertiary age. Tlie name " Age of 

 Cycads," as applied to the Secondary epoch, is therefore, 

 from a botanical point of view, an exceedingly appropriate 

 one. 



Besides Cycads, the Triassic rocks have yielded the re- 

 mains of Ferns, Uquisetitcs, Calamites, and Conifers. The 

 Ferns belong mostly to the genera 

 Neuropteris, Pecopteris, AcrosticMtcs, 

 Crematojytcris, C't/dojJteris, and Ano- 

 mopteris. A characteristic species of 

 the first of these is figured below 

 (tig. 714). The Conifers of the 

 Trias, lastly, are abundant, the most 

 characteristic oenus beino; Voltzia. 



"14. — Ncurcrjiteris dcju 



This genus is related to the existing Cypresses, and many 

 species of it are found in the Triassic rocks. 



Jurassic Plants. -^Taken as a whole, the Jurassic period 

 is characterised by tlie prevalence of Ferns, Cycads, and 

 Conifers ; no Palms or Angiospermous Exogens having been 

 as yet shown to occur. 



