300 ORDER AND SUCCESSION OF LIFE. 



Laurentian strata, it is admitted that we have an ascent to 

 corals, annelids, and Crustacea in the Cambrian, and to a 

 still higher and more abundant display of corals, star-fishes, 

 shell-fishes, annelids, and Crustacea in the Silurian. ISTot 

 only are the forms more numerous and varied, but at each 

 successive stage newer and higher orders come into view, 

 and we are compelled by evidence obtained from these early 

 systems, wherever they have been examined, to believe that 

 the march of life has been steadily onward and upward. 

 Up to this stage the living forms are wholly invertebrate 

 (that is, if we except a few doubtful instances in the upper 

 Silurians), and the plants chiefly sea- weeds and lycopods ; 

 but in the Old Red Sandstone ferns and coniferous frag- 

 ments are found, and fishes make their appearance in con- 

 siderable abundance. In the Carboniferous system, sea- 

 weeds, lycopods, ferns, equisetums, reeds, coniferous trees, 

 and numerous intermediate forms testify to a continuous 

 and gradual ascent in the flora ; while to a greater exuber- 

 ance of all the previous fauna is added the existence of 

 aquatic and terrestrial reptiles. In the earlier Secondary 

 rocks birds make their appearance, or at all events have not 

 been detected in more ancient strata; and in the upper 

 Secondaries, mammalian life of the marsupial orders begins 

 to manifest itself in increasing abundance. It is not till 

 we arrive at the Tertiary system that the higher mammals 

 occur ; and not till the Post-tertiary or Recent period that 

 we have any reliable evidence of the presence of Man, or of 

 his industrial operations. This progressive ascent in the 

 animal scale is accompanied by a similar advance in the 

 vegetable the palms and coniferse of the Secondary ages 

 being succeeded by the exogenous or true timber-trees of 

 the Tertiary, and these again by the timber-trees, fruits, and 

 cereals of the Current epoch. There may be imperfections 

 in the geological record districts unexamined, and fossil 



