450 THE TRIASSIC PERIOD 



While the Triassic flora is thus different from that of the 

 Palaeozoic, it must have given to the landscapes of the period 

 much the same appearance of graceful and luxuriant, but some- 

 what gloomy and monotonous, vegetation. Probably the fern 

 forests of New Zealand give the best modern picture of these 

 early Mesozoic woodlands. 



Of marine plants, the Calcareous Alga should be mentioned. 



Among the animals the change from Palaeozoic times is much 

 more complete than among the plants. 



Coelenterata. — Corals abounded in the seas, wherever condi- 

 tions were favourable to their growth, but the Palaeozoic Tetra- 

 coralla have died out, and their place is taken by the modern 

 Hexacoralla, though the two groups of corals approach each other 

 so closely that the distinction is not a sharp one. 



Echinodermata. — In this type a more marked change has taken 

 place. The Cystids and Blastoids have disappeared, and the Cri- 

 noids have undergone a change of structure, the Palaocrinoidea 

 giving way to the Neocrinoidea, though the latter occur only in 

 small numbers and in character rather transitional from the older 

 forms than typical of the new. Of the Triassic Crinoids much the 

 commonest, and indeed the only well-known genus, is Encrinus, 

 which is so characteristic of the German Muschelkalk ; it resem- 

 bles more the Palaeozoic than the later Mesozoic Crinoids. Simi- 

 larly, the ancient type of the Sea-urchins, the Palceoechinoidea, is 

 all but gone, only a few persisting through the Mesozoic, while the 

 Eaechinoidea, which began in a small way in the Carboniferous, 

 now come to the front. The Triassic Echinoids all belong to the 

 subclass Regulares, the irregular forms not appearing till later. 



Arthropoda. — The Crustacea and Insects of the Trias are not 

 well known, and offer no features of particular interest. 



The Bryozoa undergo a marked change in the disappearance of 

 the ancient Fenestella-like genera. 



Brachiopoda. — One of the most important changes from the 

 Palaeozoic to the Mesozoic consists in the great reduction of the 

 Brachiopods. Even in the Trias the reduction is very marked, 

 though several Palaeozoic genera have their latest representatives 



