DISTRIBUTION OF ORGANISMS. 149 



ton) and Invertebrata, and afterwards into such divisions as 

 these of the vertebrata, namely, Mammalia, Birds, Reptiles, 

 Fishes. In these grades are comprehended animals of very 

 various character, animals which only agree in this particular 

 of a community of grade or rank. But other divisions in the 

 common classifications are into groups or series of animals 

 closely allied to each other in form and of one general cha- 

 racter, as, for example, the cephalopoda, the echinodermata, 

 the Crustacea. The one kind of division may be said to be 

 transverse, the other longitudinal. Such a diversity gives 

 rise to a suspicion that there is something wrong, something 

 out of accordance with nature. And so it is. The true 

 fundamental divisions are entirely of the latter kind longi- 

 tudinal ; there only do we find persistence of characters ; the 

 other so-called divisions are only the marks of stages which 

 the true divisions, the Stirpes of being, have reached in their 

 respective courses. It is nevertheless necessary, in the mean- 

 time, to keep the existing classification in view, and to use 

 its language, in order that my own views may be intelligible. 



Cuvier divided the Invertebrata into three great masses, 

 the Radiata, the Articulata, and Mollusca. Of these the tw 

 last appear as co-ordinate, though distinct from each other ; 

 while the Radiata, again, may, excepting one class, be con- 

 sidered as forming a kind of basis for the whole kingdom. 



The RADIATA are all of them animals of exceedingly simple 

 structure, mostly inhabitants of the waters, many of them pro- 

 pagating not by ova, but by division of their bodies, or by the 

 throwing out of little bud-like excrescences. In this lower 

 region are comprehended the Infusory animalcules, Internal 

 Parasites (Entozoa), Sponges, Polyps, Sea-nettles (Acalephcz), 

 and some other obscure classes. Some of these appear to be 

 distinct and independent series, which advance no further ; 

 such, in particular, are the internal parasites, which necessarily 

 do not pass to any higher grade, because they have no sphere 

 for further development. Others form the roots, as it were, 

 of higher families. 



There are two admitted methods of investigating the affi- 

 nities of beings. One is to observe the connexion between the 



