ORDERS AMONG ANIMALS. 233 



racterized with as much precision, and their specific charac- 

 ters to be described with as much minuteness, as if a host 

 of them, although not yet known, existed besides. It is a 

 very objectionable practice among zoologists and botanists 

 to remain satisfied in such cases with characterizing the 

 genus, and perhaps to believe, what some writers have 

 actually stated distinctly, that in such cases generic and 

 specific characters are identical. 



Such being the natural relations and the subordination 

 of branches, classes, orders, families, genera, and species, I 

 believe, nevertheless, that neither branches, nor classes, 

 (orders of course not at all,) nor families, nor genera, nor 

 species, have the same standing when compared among 

 themselves. But this does not in the least interfere with 

 the prominent features of orders, for the relative standing 

 of branches, or classes, or families, or genera, or species, 

 does not depend upon the degrees of complication of their 

 structures as that of orders does, but upon other features, 

 as I will now show. The four great types or branches of 

 the animal kingdom, characterized as they are by four 

 different plans of structure, will each stand higher or 

 lower, as the plan itself bears a higher or lower character, 

 and to show this to be the case we need only compare 

 Vertebrata and Eadiata. 1 The different classes of one 

 type will stand higher or lower, as the ways in which, and 

 the means with which, the plan of the type to which they 

 belong is carried out, are of a higher or lower nature. 

 Orders in any or all classes are of course higher or lower, 

 according to the degree of perfection of then- representa- 

 tives, or according to the complication or simplicity of 



1 I must leave out the details of moreover, any text-book of cornpara- 

 such comparisons, as a mere mention tive anatomy will furnish the com- 

 of the point suffices to suggest thorn; plete evidence to that effect. 



