176 ESSAY ON CLASSIFICATION. Part I. 



during the embryonic growth, in the order of their subordination, there was no 

 possibiUty of deriving from embryological monographs, that information upon this 

 point, so much needed in Zoology, and so seldom alluded to by embryologists. 

 Again, without knowing what constitutes truly the characters of the groups named 

 above, there is no possibility of finding out the true characters of a genus of 

 which only one species is known, of a family which contains only one genus, etc., 

 and for the same reason no possibility of arriving at congruent results with refer- 

 ence to the natural limitations of genera, families, orders, etc., without which Ave 

 cannot even begin to build up a permanent classification of the animal kingdom ; 

 and still less, hope to establish a solid basis for a general comparison between 

 the animals now living and those which have peopled the surface of our globe 

 in past geological ages. 



It is not accidentally I have been led to these investigations, but by necessity. 

 As often as I tried to compare higher or more limited groups of animals of the 

 present period with those of former ages, or early stages of growth of higher living 

 animals with full-grown ones of lower types, I was constantly stopped in my 

 progress by doubts as to the equality of the standards I was applying, until I 

 made the standards themselves the object of direct and very extensive investiga- 

 tions, covering indeed a much wider ground than would appear from these remarks, 

 for, upon these principles, I have already remodelled, for my ovm convenience, nearly 

 the whole animal kingdom, and introduced in almost every class very unexpected 

 changes in the classification. 



I have already expressed above ^ my conviction that the only true system is 

 that which exists in nature, and as, therefore, no one should have the ambition 

 of erecting a system of his own, I will not even attempt now to present these 

 results in the shape of a diagram, but remain satisfied to express my belief, that 

 all we can really do is, at best, to offer imperfect translations in human language 

 of the profound thoughts, the innumerable relations, the unfathomable meaning of 

 the plan actually manifested in the natural objects themselves ; and I should con- 

 sider it as my highest reward should I find, after a number of years, that I had 

 helped others on in the right path. 



* See Clmp. I., Sect. 1, p. 7-9. 



