S6 ///. ARTIFICIAL KEY FOR THE 



** Locomotive, or at least unattached, 

 f Body worm-like, round or flat. 

 No shell. 



J Body cylindrical, usually 

 pointed at the anterior 

 end; mostly parasitic. 



Nematelminihes, sub 



Vermes. 



W Body flattened and capable 



of considerable elongation 



and contraction ; mostly 



parasites. 



Plaiyhelminthes, sub 

 Vermes. 

 WX Anterior portion cylindri- 

 cal, succeeded by a nar- 

 row zone, the ' ' collar. 

 Posterior portion some- 

 what flattened, live in 

 burrows in sand of sea- 

 coast. 



Enleropneusta, sub Pre- 

 vertebrata. 

 •|"|- Body not worm-like. 



\ Body soft and slimy, covered 

 dorsally by an integu- 

 mental duplicature, the 

 mantle, which usually se- 

 cretes a shell; marine, 

 fresh-water, and terrestrial 

 forms. 



MoUusca. 



J J Pelagic, transparent forms; 



cask-shaped and with 



zone-like bands. 



Thaliacea, sub Preverte- 



brata. 



