APPARITION OF SPECIES 99 



many cases, to groups now very rare; while the 

 commoner tribes of modern fish do not appear. On 

 the land batrachian reptiles now abound, some of them 

 very high in the sub-class to which they belong. 

 Scorpions, spiders, insects, and millipedes appear, as 

 well as land-snails ; and this not in one locality only, 

 but over the whole northern hemisphere. At the 

 same time the land was clothed with an exuberant 

 vegetation not of the lowest types nor of the highest, 

 but of intermediate forms, such as those of the pines, 

 the club-mosses, and the ferns, all of which attained 

 in those days to magnitudes and numbers of species 

 unsurpassed, and in some cases unequalled, in the 

 modern world. Nor do they show any signs of an 

 unformed or imperfect state. Their seeds and spores, 

 their fruits and spore-cases, are as elaborately con 

 structed, the tissues and forms of their stems and 

 leaves as delicate and beautiful, as in any modern 

 plants. Nay, more ; the cryptogamous plants of this 

 age show a complexity and perfection of structure 

 not attained to by their modern successors. So with 

 the compound eyes and filmy wings of insects, the 

 teeth, bones, and scales of batrachians and fishes ; all 

 are as perfectly finished, and many quite as complex 

 and elegant, as in the animals of the present day. 



This wonderful Palaeozoic age was, however, but 

 a temporary state of the earth. It passed away, and 

 was replaced by the Mesozoic, emphatically the reign 

 of reptiles, when animals of that type attained to 



G 2 



