THE GREAT STEMS OF THE PEDIGREE. 43 



torical developttient. Our tribes, or phyla, according to this 

 idea, essentially coincide with those few " great classes," or 

 " main classes," of whichDarwin also thinks that each contains 

 only organisms related by blood, and of which, both in the 

 animal and in the vegetable kingdoms, he only assumes either 

 four or live. In the animal kingdom these tribes would essen- 

 tially 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. i. 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 : — 1. Flowering plants (Phanerogamia) ; 

 2. Ferns (Filicinae) ; 3. Mosses (Muscinae) ; 4. Lichens 

 (Lichenes) ; 5. Fungi (Fungi) ; and 6. Water-weeds (Algte). 

 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 



