356 Mr. H. E. Strickland on the Structural 



the secondary subdivisions are grounded on the organs of re- 

 spiration, groups of a lower rank on the digestive system, and 

 so on, the most superficial peculiarities, such as external form 

 and colour, being reserved to characterize the ultimate groups 

 of genera and species. These improved principles of classi- 

 fication are gradually bringing the systems of Zoology and 

 Botany into a state of permanence, consistent with Nature, 

 and satisfactory to that Truth-seeking Instinct which is inhe- 

 rent in the human mind. 



A further advance of philosophical Classification has shown 

 that the characters of organized beings require not only to be 

 subordinated according to their importance, but subdivided 

 according to their kinds. There are many instances of cor- 

 respondence of structural characters in organic beings which 

 can never by any process of subordination become elements 

 in a natural classification, and it is important to distinguish 

 those which can from those which cannot be so employed. 

 Zoologists had long been aware that certain sets of characters 

 produced an arbitrary or artificial method if employed for 

 classification, while others seemed to lead to a natural system, 

 but the question was involved in obscurity till the time of 

 MacLeay, who was the first to give us clear definitions on the 

 distinction between Affinity and Analogy. He applied 

 his views indeed in support of a theory, the Quinary System, 

 which few naturalists are now disposed to support, and with 

 which we are not now concerned ; but his elucidation of Affi- 

 nities and Analogies is not the less valuable on that account. 

 Although I am not disposed to take the same view of these 

 principles as that of Mr. MacLeay, yet as the principles them- 

 selves are at the foundation of all sound classification, whether 

 in Zoology or Botany, I may be allowed to make a few further 

 remarks upon this subject. 



It appears to me that the instances of resemblance or agree- 

 ment of structure between any two species of organized beings 

 should be reduced, not into two, but into three distinct classes, 

 Affinity, Analogy, and a third, for which I propose to adopt 

 the name of Iconism*. 



I. The highest class of these structural agreements is that 

 of Affinities, which appear to be the direct result of those 

 Laws of Organic Life which the Creator has enacted for his 

 own guidance in the act of Creation. Affinity consists in an 

 essential and physiological agreement in the corresponding 

 parts of organic beings, resulting from a uniformity of plan 



* This term, suggested by the Rev. Dr. Ingram, President of Trinity 

 College, appears preferable to Mimesis, which I had originally proposed to 



