236 



EXPLANATIONS. 



reptilia occur in those early strata where their remains 



xnd vestiges are few. In as far as it may be taken as a 

 positive fact, I only claim a modified benefit from it, be 

 cause the view which I take of the affinities and connec 

 tions of the animal kingdom (and by analogy of the vege- 

 table kingdom also) makes it a matter of less consequence 

 than would be generally supposed, which order of any 

 class appears first in the stone record, though still per- 

 haps a matter of some consequence. 



This view suggests that development has not pro- 

 ceeded, as is usually assumed, upon a single line which 

 would require all the orders of animals to be placed one 

 after another, but in a plurality of lines in which the 

 orders, and even minuter subdivisions of each class, are 

 ranged side by side. It also suggests that the develop- 

 ment of these various lines has proceeded independently 

 in various regions of the earth, so as to lead to forms not 

 everywhere so like as to fall within our ideas of specific 

 character, but generally, or in some more vague degree, 

 alike. The progress of the lines becomes clearest when 

 we advance into the vertebrate sub-kingdom. We can 

 there trace several of them with tolerable distinctness, 

 as they singly pass through the four classes of Fishes, 

 Reptiles, Birds, and Mammals ; the Birds, however, 

 being a branch in some part derived equally with the 

 reptiles from fishes, and thus leaving some of the mam- 

 mal order in immediate connection with the reptiles. 

 The lines or stirpes have all of them peculiar characters 

 which persist throughout the various grades of being 

 passed through, one presenting carnivorous, another gen- 

 tle anJ innocent animals, and so on. We have, there- 

 fore, in the animal kingdom, not one long range of af- 

 finities, but a number of short series, in each of which 

 a certain general character is observable, though not 

 always to the exclusion of the organic peculiarities of 

 families in neighboring lines, especially in the class of 

 reptiles. 



According to this view, the matrix of organic life is, 

 speaking generally, the sea. Fluid, required for all em- 

 Dryotic conditions, is also necessary to the origination of 

 the various stirpes of both kingdoms. The whole of the 

 lowest animal sub-kingdom (Radiata) is aquatic ; so are 

 neur.v the Mollusca and a very large proportion of the 

 Articulata. In the Vertebrata, the lowest class also is 



