416 



MESOZOIC ERA— AGE OF REPTILES. 



J 



The flora of the Trias is very imperfectly known. We find, how- 

 ever, no longer the great coal-making trees of the Carboniferous — Sig- 

 illarids, Lepidodendrids, and Calamites — though 

 Tree-ferns still continue in abundance, but of differ- 

 ent types from those of the coal. The forest-trees 

 seem to have been principally Tree-ferns, Cycads, 

 and Conifers, although the last two did not reach 

 their highest development until the next period. 

 For this reason we will put off the fuller discussion 

 of them until we come to that period. 



Animals. — Among Echinoderms we find no longer 

 any Oystids and Blastoids; but Crinids, beautiful 

 Encrinites, with long plumose arms, are very 

 abundant (Fig. 601). 



Among Brachiojpods the familiar square-shoul- 



Fig. 601.— Encrinus liliformis. 



Fig. 602.— Aspidura loricata, an asteroid. 



dered forms, including the Spirifer family, the Strophomena family, and 

 the Productus family, are almost if not wholly gone ; only a few Spiri- 

 fers remain. Among Cephalopods, we find no longer Orthoceratites 

 or Goniatites, but Ceratites (Fig. 609) take their place, and Ammo- 

 nites begin. In Ceratites, the suture is more complex than in Gonia- 

 tites, but not so complex as the subsequent Ammonites. Among Crus- 

 taceans, we find no longer TriloUtes nor huge Eurypterids, but Mac- 

 rourans, which began in the Carboniferous, are now more abundant, 

 and of more modern forms (Fig. 610). 



Insects. — As already seen, all the hexapod insects of Palaeozoic be- 

 long to one family — the Palaeodictyoptera — but this was a generalized 

 type connecting the three lower existing orders, viz., Orthopters, Neu- 

 ropters, and Hemipters. Now, with the opening of the Trias, we have 

 these three orders distinctly differentiated, and Coleopters (beetles) 

 added (Fig. 611). But still the sucking insects are wanting. 



Fishes. — Among fishes, still we find no Teleosts, only Ganoids and 

 Placoids ; but while the Ganoids are some of them heterocercal or ver- 

 tebrated-tailed like the Palaeozoic Ganoids, some are only slightly ver- 

 tebrated, and some wholly non-vertebrated-tailed, or homoceral. The 

 Ceratodus, a remarkable genus of fishes, one species of which still lives 



