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Explanation of Diagram illustrating the relations between Families, Genera, 
Spectes, Varieties and Individuals. 
Each dot in the clusters represents an individual. and distance apart is 
supposed to indicate degrees of difference in characters. The dotted boundary 
lines enclose genera, and I. II. III. indicate families. 
Family I. has four genera, A. B.C. and D. A. is a genus with eight species 
(or aggregations of more or less similar individuals) arranged in three groups. 
In such a case some systematists might break A. up into three allied genera. 
Species 3 and 4 are shown as almost continuous groups of individuals; they 
are closely allied species, and some systematists would say that they form 
merely two varieties of the same species: 8 represents a larger species with 
many individuals. B. C. and D. are three allied genera only a little more 
separated from one gnother than the three groups of species in A. in the line 
above. B. has two closely allied species. C. has six distinct species. D. isa 
genus formed for a single isolated species. 
Family II. is a small isolated group of two species forming one genus E. 
Family III. comprises a number of closely allied species, most of which 
(1-10) are so variable and so closely related that it would become a matter of 
opinion amongst systematists whether they ought to be regarded as all distinct 
species or as varieties of one large variable species. 
