li6 VESTIGES OF THE 



appear to liave prevailed at the close of the coal formation 

 ill P_]ngland and thi'oiighout the tertiary era. The surface 

 has also undergone a gradual progress by which it has 

 become always more and more variegated and thereby 

 fitted for the residence of a higher class of animals. 



In pursuing the progress of the development of both 

 plants and animals upon the globe, we have seen an 

 advance in both cases, along the line — or, it may 

 l)e, lines — leading to the higher forms of organisation. 

 Amongst plants, we have first sea-weeds, afterwards land 

 plants; and amongst these the simpler (cellular and 

 cryptogamic) before the more complex. In the depart- 

 ment of zoology, we see zoophytes, radiata, mollusca, 

 articulata, existing for ages before there were any higher 

 forms. The first step forward gives fishes, the humblest 

 class of the vertebrata ; and, moreover, the earliest fishes 

 partake of the character of the next lowest sub-kingdom, 

 the articulata. Afterwards come land animals, of which 

 the first are reptiles, universally allowed to be the type 

 next in advance from fishes, and to be connected with 

 these by the links of an insensible gradation. From 

 reptiles we advance to birds, and thence to mammalia, 

 which are commenced by marsupialia, acknowledgedly 

 low forms in their class. That there is thus a progress 

 of some kind, the most superficial glance at the geological 

 history is sufiicient to convince us. Indeed the doctrine 

 of the gradation of animal forms has received a remark- 

 able support from the discoveries of tliis science, as 

 f-everal types formerly wanting to a completion of the 

 series have been found in a fossil state.* 



It is scarcely less evident, from the geological record, 



•'• Intervals in tVie scries were nuinerous in the department of the 

 jniehyck'nnata ; many of these gaps are now filled np from the extinct 

 genera found in the tertiary formation. 



