PARTS OF ANIMAI^ 



Note on the Four Classes of Bloodless Animals. — 

 These, in order of increasing softness, as noted 

 above, are the following (I give the Greek term, its 

 literal translation, and the term which I have used 

 to translate it in this volume) : 



τά ΐντομα insected animals Insects 



τά οστρακόδερμα shell-skinned animals Testacea 



TO. μαλακόστρακα soft-shelled animals Crustacea 



τά μαλάκια softies Cephalopods 



In using " Testacea " to translate τά οστρακόδερμα 

 (" the animals with earthenware skins "), I use 

 it in the old-fashioned sense, so as to include a 

 number of shelled invertebrates, comprising Gastero- 

 pods, Lamellibranchs, and some Echinoderms. It 

 does not refer to the Testacea of modern zoologists, 

 by whom the term is applied to the Foraminifera 

 which are shelled Protozoa. The word " Ostraco- 

 derms " (a transliteration of Aristotle's word) is now 

 given by zoologists to a group of primitive fossil 

 fishes. 



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