FAMILY CHARACTERISTICS. 111 
plants that naturalists first perceived those gen- 
eral traits of resemblance existing everywhere 
among the members of natural families, in con- 
sequence of which they added this kind of group 
to the framework of their system. In France, 
particularly, this method was pursued with suc- 
cess; and the improvements thus introduced by 
the French botanists were so great, and rendered 
their classification so superior to that of Linne- 
us, that the botanical systems in which Families 
were introduced were called natural systems, in 
contradistinction especially to the botanical clas- 
sification of Linneus, which was founded upon 
the organs of reproduction, and which received 
thenceforth the name of the sexual system of 
plants. The same method. so successfully used 
by botanists was soon introduced into Zodlogy 
by the French naturalists of the beginning of 
this century, — Lamarck, Latreille, and Cuvier. 
But, to this day, the limitation of Families among 
animals has not reached the precision which it 
has among plants, and I see no other reason for 
the difference than the absence of a leading prin- 
ciple to guide us in Zodlogy. 
Families, as they exist in Nature, are based up- 
on peculiarities of form as dependent upon struc- 
ture; but though a very large number of them 
have been named and recorded, very few are char- 
acterized with anything like scientific accuracy. 
