CLASSIFICATION OF THE ANIMAL KINGDOM 4 



ognized. They may be of use in some circumstances but seem to be of 

 little value in showing the arrangement of the orders on a practical 

 basis. 



Throughout, rejected synonyms are printed in itaUcs, the accepted 

 class names are in capital letters, and the subclass names and the order 

 names are both set in capitals and lower case letters. In the footnotes, 

 names that also appear in the classification above are printed in small 

 capitals. The other names in the footnotes are somewhat in the nature 

 of rejected synonyms, but as most of them are really the names of non- 

 accepted groupings, they appear in capitals and lower case roman letters. 



To the variety of spellings there is no end. No attempt is made to 

 list all forms, but such spellings as would appear at a separate place in 

 an alphabetical index are listed, along with those variations that are 

 used for distinct levels; e.g., Echiuroidea (phylum), Echiurida (class), 

 and Echiuroina (order). 



In the Complete List of Orders the geologic range of each group 

 is shown by symbols at the right margin. The meaning of these symbols 

 is shown in the following table. 



REC Recent JUR Jurassic 



QUA Quaternary mes Mesozoic 



PLE Pleistocene per Permian 



PLI Pliocene pen Pennsylvanian 



OLI Oligocene mis Mississippian 



Mio Miocene car Carboniferous 



EOC Eocene (+ Paleocene) dev Devonian 



ter Tertiary sil Silurian 



CEN Cenozoic ord Ordovician 



CRE Cretaceous cam Cambrian 



TRI Triassic pal Paleozoic 



There are a few points of discrepancy between the Simplified List 

 and the Complete List. These are intentional, to make the simplified 

 list more useful to students. The Complete List shows the definitive 

 classification that is here being proposed. 



The names included under the footnote heading "Includes" may 

 be suborders, synonyms, rejected groups, or names of questionable ap- 

 plication. They are all names which have at some time been used for 

 orders or more inclusive groups and are included merely to indicate 

 their approximate position in the scheme. 



