FUNDAMENTAL RELATIONS OF ANIMALS. 5 



careful attention to this subject, and to make special in- 

 vestigations for its solution. 



Before I proceed any further, however, I would submit 

 one case to the consideration of my reader. Suppose that 

 the innumerable articulated animals, which are counted 

 by tens of thousands, nay, perhaps by hundreds of thou- 

 sands, had never made their appearance upon the surface 

 of our globe, with one single exception: suppose, for in- 

 stance, that our Lobster (ffomarus americanus) were the 

 only representative of that extraordinarily diversified type, 

 -how should we introduce that species of animal into our 

 systems 1 Simply as a genus with one species, by the side 

 of all the other classes with their orders, families, etc., or 

 as a family containing only one genus with one species, 

 or as a class with one order and one genus, or as a class 

 with one family and one genus 1 And should we acknow- 

 ledge, by the side of Vertebrata, Mollusca, and Badiata, 

 another type, Articulata, on account of the existence of 

 that one Lobster, or would it be natural to call it by a 

 single name, simply as a species, in contradistinction to 

 all other animals 1 It was the consideration of this sup- 

 posed case which led me to the investigations detailed 

 below, which, I hope, may end in the ultimate solution of 

 this apparently inextricable question. 



Though what I have now to say about this supposed 

 case cannot be fully appreciated before reading my remarks 

 in the following chapter, 1 respecting the character of the 

 different kinds of groups adopted in our systems, it must 

 be obvious that our Lobster, to be what we see this ani- 

 mal is, must have had its frame constructed upon that very 

 same plan of structure which it exhibits now. And, if I 

 should succeed in showing that there is a difference be- 



1 See Chap. II. 



