THE VEGETABLE AND ANIMAL KINGDOMS. 133 



racters of the remaining groups" of echinodermata. The 

 earliest Cephalopods were not the most typical. The first 

 Fishes exhibit a remarkable assemblage of characters, some 

 leaning to the invertebrate grade, others rising towards the 

 reptilian form, while the more typical fishes came afterwards. 

 " When we look at the earliest forms of reptilian life, of which 

 we have any cognizance, we find them to present very remark- 

 able combinations of the characters which are now distributed 

 among different groups. Thus the Labyrinthodon of the 

 Triassic formation appears to have been essentially Batrachian 

 in its structure, but to have possessed some characters of the 

 Crocodilian order. And the same formation contains remains 

 of reptiles, which, while essentially Saurian in their general 

 structure, had the horny mandibles, and probably many other 

 characters of the Chelonia. In the early history of the class of 

 Mammalia, so far as known to us, the same general plan may be 

 traced. The only order that is distinctly recognisable by re- 

 mains preserved in the secondary strata, is that of Marsu- 

 pialia, which has much in common with the Oviparous Verte- 

 brata. Near the commencement of the Tertiary epoch, 

 remains of Pachydermata are abundant ; but these were for 

 the most part different from those of the present epoch, con- 

 taining combinations of characters which are now distributed 

 among several distinct families, and presenting also a closer 

 approximation to the herbivorous cetaceans on the one hand, 

 and to the ruminants on the other, than is exhibited by any 

 existing species of the order. So among' the early Edentata 

 we meet with a group now entirely extinct, which connected 

 that order with the massive pachyderms." 1 



The history of fossil plants, as far as known, exhibit traces 

 of the same law ; " the characteristic flora of the coal forma- 

 tion appearing to have been chiefly composed of coniferse, 

 which constitute a connecting link between the Phanerogamia 

 and Cryptogamia ; and of these coniferse, while some ^ may 

 have been nearly allied to existing forms, the great majority 

 appear to have presented such a combination of the characters 

 of the coniferae with those of the higher cryptogamia, as no 

 existing group exhibits." 



Now it must be at once admitted, that we do not possess 

 such an intimate and exact knowledge, either of the history of 

 life on the globe or of the embryonic history of an individual 

 organism of the highest rank, as to entitle us to say that there 



1 Carpenter, Gen. Phys. 345. 



