Corona Radiata

Or Leaf crown,Crown of bristles,

In Nematodes:The border of the labial region divided into a series of leaf-like structures,found in certain Strongyles.There may be two circles of leaf-like structures termed the Internal and External Corona(=Internal and External leaf crowns of some Authors)The number of elements is diferent among different nematodes( 6 in Deletrocephalus dimidiatus to 80  in Strongylus equinus)

Both two internal and external crowns exist: e.g.  Oesophagostomum spp

Rarely the two leaf crowns may be fused: e.g.  Chabertia ovina

Sometimes the two leaf crowns may be reduced to a single leaf crown: e.g. Cyclicodontostomum purvisi 

 Sometimes they are reduced to Hook-like elements: e.g. Agriostomum