238 ESSAY ON CLASSIFICATION. 



In the first place, when form is considered as character- 

 istic of Kadiata or Articulata, or any other of the great 

 types of the animal kingdom, it is evident that it is not a 

 definite outline and well determined figure which is 

 meant, but that here the word form is used as a synonym 

 for plan. Who, for instance, would describe the tubular 

 body of an Holothuria as characterized by a form similar 

 to that of the Euryale, or that of an Echinus as identical 

 with that of an Asterias ? And who does not see, that, as 

 far as the form is concerned, Holothurise resemble Worms 

 much more than they resemble any other Echinoderm, 

 though, as far as the plan of their structure is concerned, 

 they are genuine Kadiates, and have nothing to do with 

 the Articulates'? 



Again, a superficial glance at any and all the classes of 

 the animal kingdom is sufficient to show that each con- 

 tains animals of the most diversified forms. What can 

 be more different than Bats and Whales, Herons and Par- 

 rots, Frogs and Sirens, Eels and Turbots, Butterflies and 

 Bugs, Lobsters and Barnacles, Nautili and Cuttlefishes, 

 Slugs and Conchs, Clams and compound Ascidians, Pen- 

 tacrinus and Spatangus, Beroe and Physalia, Actinia and 

 Gorgonia ? And yet they belong respectively to the same 

 class, as they are coupled here : Bats and Whales toge- 

 ther, etc. It must be obvious, then, that form cannot be 

 a characteristic element of classes, if we intend to desig- 

 nate anything definite under that name. 



But form has a definite meaning, understood every- 

 where, when applied to well-known animals. We speak, 

 for instance, of the human form; an allusion to the form 

 of a horse or that of a bull conveys at once a distinct idea; 

 everybody would acknowledge the similarity of form of 

 the horse and ass, and knows how to distinguish them by 



