hemielytrum

from The Century Dictionary.

• noun The fore wing of hemipterous and especially heteropterous insects, coriaceous at the base and membranous at the tip, whence the name.
• noun In Vermes, one of the large imbricated scales which lie in double series along the back of certain scale-bearing marine annelids, as the sea-mice or Aphroditidœ.
• noun Also hemelytrum, hemelytron.