ANIMAL LIFE GENERATION. 353 



for ourselves in this field, we shall throw 

 into the following brief summary. Of the 

 Metazoan system we make three divisions. 



A. THE PLANT-ANIMALS or Phytoids, 

 which must be carefully distinguished from 

 the previously mentioned Phytozoa, in which 

 there is as yet no differentiation. But the 

 Phytoid is decidedly an animal in function, 

 though in form it is like a plant, and is often 

 named from this resemblance (as the crenoid 

 or sea-lily). These animals we place first and 

 lowest, since they have not yet fully gotten 

 rid of the vegetal formative process, which 

 they have in common with the Plant. Thus 

 they must be considered to stand nearest to 

 the primal bifurcation of the life-stuff into 

 Plant and Animal. Such are the sponges, 

 star-fishes, echinoderms (once known as radi- 

 ates, now called chiefly coelenterates). We 

 may also observe that Phytoids are in the 

 process of getting rid of their vegetal form, 

 which likewise has or may have a skele- 

 ton (as can be seen in the star-fish). Indeed 

 the skeletal criterion of classification may be 

 conceived to run through the whole gamut 

 of Animal-life from the Phytoids to the Ver- 

 tebrates, though sometimes it is not so easy 

 to find. 



B. THE MOLLUSKS may be put next as the 

 intermediate or transitional stage, though 



