KEUPER FORMATION. 



group usually consists of a numerous series of mottled marls, of a 

 red, greenish grey, or blue colour, which pass into green marls, 

 black slaty clays, and fine-grained sandstones. Throughout the 

 series, common rock-salt and gypsum are abundant, but the 

 organic remains of animals are extremely rare. Of plants, how- 

 ever, a considerable number are preserved in some localities ; and 



Fig. 67. Volt'zia ketcro'pliylla. 



these indicate a wide departure from the carboniferous period, and, 

 as well as the shells, seem to 

 possess more analogies with the 

 forms of life determined from the 

 fossils of the secondary period, than 

 with those common in palse'ozoic 

 rocks. Besides peculiar species 

 of ferns, the trias presents us with 

 fossil plants not previously met 

 with. In the sandstone are par- 

 ticular species of co'nifers which 

 constitute the genus Volt'zia, (Jig. 

 67), and in the limestone, remains 

 of cyc'adeas of the genus manfe/lia; 

 ihis last family is very abundant 

 in the Keuper, in which are found 

 the genus Nttso'nia, and the genus 

 Plerophylhtm, (Jig. 8). Several 

 species of large saurian reptiles 

 are also found in the trias group 

 of rocks. Fig-,68, Ple'rophyllumPlfiriinge'rH 



5* 



