COMMUNITIES 37 
munities based upon minor differences in habitats, and formations based 
upon larger major differences in habitats. 
We give the communities of different orders below with taxonomic 
divisions of corresponding magnitude opposite for comparison. With 
the exception of the first, these taxonomic groupings do not bear the 
slightest relation to the ecological groupings, but are added to indicate 
magnitude. 
Ecological Groups Taxonomic Groups 
(Mos) mores Form (forms) (species) 
Consocies Genus 
Stratum or story Family 
Association or society Order 
Formation Class 
Extensive formation Phylum 
(Aquatic and terrestrial) (Vertebrates and invertebrates) 
Mores, in the technical sense in which the term is used here, are 
groups of organisms in full agreement as to physiological life histories 
as shown by the details of habitat preference, time of reproduction, 
reactions to physical factors of the environment, etc. The organisms 
constituting a mores usually belong to a single species but may include 
more than one species as specificities of behavior are not significant (13). 
Consocies are groups of mores usually dominated by one or two of the 
mores concerned and in agreement as to the main features of habitat 
preference, reaction to physical factors, time of reproduction, etc. 
Example: the prairie aphid consocies. The aphids dominate a group 
of organisms which for the most part prey upon them, as, for instance, 
certain species of lacewing, lady beetles, syrphus-flies, etc. (13). 
Strata are groups of consocies occupying the recognizable vertical 
divisions of a uniform area. Strata are in agreement as to material for 
abode and general physical conditions but in less detail than the consocies 
which constitute them (13). 
For example, a forest-animal community is clearly divisible into the 
subterranean-ground stratum, field stratum (zone of the tops of the 
herbaceous vegetation), the shrub stratum (zone of the tops of the 
dominant shrubs), the lower tree stratum (zone of the shaded branches 
of the trees), and the upper tree stratum. A given animal is classified 
primarily: with the stratum in which it breeds, as being most important 
to it, and secondarily with the stratum in which it feeds, etc., as in many 
cases most important to other animals. The migration of animals from 
