THE WORMS. 147 
The third tribe of the animal kingdom, the phylum of 
Worms or worm-like animals (Vermes, or Helminthes), con- 
tains a number of diverging branches. Some of these 
numerous branches have developed into well-marked and 
perfectly independent classes of Worms, but others changed 
long since into the original, radical forms of the four higher 
tribes of animals. Each of these four higher tribes (and 
likewise the tribe of Zoophytes) we may picture to ourselves 
in the form of a lofty tree, whose branches represent the 
different classes, orders, families, etc. The phylum of Worms, 
on the other hand, we have to conceive as a low bush or 
shrub, out of whose root a mass of independent branches 
shoot up in different directions. From this densely 
branched shrub, most of the branches of which are dead, 
there rise four high stems with many branches. These 
are the four lofty trees just mentioned as representing the 
higher phyla—the Echinoderma, Articulata, Mollusca, and 
Vertebrata. These four stems are directly connected with 
one another at the root only, to wit, by the common primary 
group of the Worm tribe. 
The extraordinary difficulties which the systematic ar- 
rangement of Worms presents, for this reason merely, are 
still more increased by the fact that we do not possess any 
fossil remains of them. Most of the Worms had and still 
have such soft bodies that they could not leave any 
characteristic traces in the neptunic strata of the earth. 
Hence in this case again we are entirely confined to the 
records of creation furnished by ontogeny and comparative 
anatomy. In making then the exceedingly difficult at- 
tempt to throw a few hypothetical rays of light upon the 
obscurity of the pedigree of Worms, I must therefore 
