178 THE GEOLOGICAL HISTORY OF PLANTS. 



Cretaceous. It will thus be convenient to confine our- 

 selves in this chapter to the flora of the earlier Mesozoic. 



Passing over for the present the cryptogamous plants 

 already familiar in older deposits, we may notice the new 

 features of gymnospermous and phsenogamous life, as they 

 present themselves in this earlier part of the great rep- 

 tilian age, and as they extended themselves with remark- 

 able uniformity in this period over all parts of the world. 

 For it is a remarkable fact that, if we place together in 

 our collections fossil plants of this period from Australia, 

 India, China, Siberia, Europe, or even from Greenland, 

 we find wonderfully little difference in their aspect. This 

 uniformity we have already seen prevailed in the Palaeo- 

 zoic flora ; and it is perhaps equally marked in that of 

 the Mesozoic. Still we must bear in mind that some 

 of the plants of these periods, as the ferns and pines, 



for example, are still 

 world-wide in their 

 distribution ; but this 

 does not apply to oth- 

 ers, more especially 

 the cycads (Fig. 65). 



The cycads consti- 

 tute a singular and ex- 

 ceptional type in the 

 modern world, and 

 are limited at present 

 to the warmer cli- 

 mates, though very 

 generally distributed 

 in these, as they oc- 

 cur in Africa, India, 

 Japan, Australia, Mexico, Florida, and the West Indies. 

 In the Mesozoic age, however, they were world-wide in 

 their distribution, and are found as far north as Green- 

 land, though most of the species found in the Cretaceous 



Fig. 65. — Podozamites lanceolatus, Sternb. 

 L. Cretaceous. 



