THE GREAT STEMS OF THE PEDIGREE, 43 
torical development. Our tribes, or phyla, according to this 
idea, essentially coincide with those few “great classes,” or 
“main classes,” of which Darwin also thinks that each contains 
only organisms related by blood, and of which, both in the 
animal an] in the vegetable kingdoms, he only assumes either 
four or five. In the animal kingdom these tribes would essen- 
trally coincide with those four, five, or six main divisions 
which zoologists, since Bar and Cuvier, have distinguished as 
“main forms, general plans, branches, or sub-kingdoms” of 
the animal kingdom. (Compare vol.1. p. 53.) Bar and Cuvier 
distinguished only four of them, namely :—1. The vertebrate 
animals (Vertebrata); 2. The articulated animals (Articulata); 
3. The molluscous animals (Mollusca); and 4. The radiated 
animals (Radiata). At present six are generally distinguished, 
since the tribe of the articulated animals is divided into two 
tribes, those possessing articulated feet (Arthropoda), and the 
worms (Vermes) ; and in like manner the tribe of radiated 
animals is subdivided into the two tribes of the star animals 
(Echinodermata) and the animal-plants (Zoophyta). Within 
each of these six tribes, all the included animals, in spite of 
great variety in external form and inner structure, never- 
theless possess such numerous and important characteristics 
in common, that there can be no doubt of their blood 
relationship. The same applies also to the six great main 
classes which modern botany distinguishes in the vegetable 
kingdom, namely :—1l. Flowering plants (Phanerogamia) ; 
2. Ferns (Filicine); 3. Mosses (Muscine); 4. Lichens 
(Lichenes) ; 5. Fungi (Fungi); and 6. Water-weeds (Alyz). 
The last three groups, again, show such close relations to one 
another, that by the name of “ Thallus plants” they may be 
contrasted with the three first main classes, and consequently 
