The Collaborative International Dictionary of English v.0.48:

Hemelytron \Hem*el"y*tron\ (? or ?), Hemelytrum \Hem*el"y*trum\
   (-tr[u^]m cf. Elytron, 277),, n.; pl. Hemelytra. [NL. See
   Hemi, and Elytron.] (Zool.)
   One of the partially thickened anterior wings of certain
   insects, as of many Hemiptera, the earwigs, etc.
   [1913 Webster]