retinulae

from The Collaborative International Dictionary of English v.0.48

Retinula \Re*tin"u*la\, n.; pl. {Retinulae}. [NL., dim. of NL. &
   E. retina.] (Zool.)
   One of the group of pigmented cells which surround the
   retinophorae of invertebrates. See Illust. under
   {Ommatidium}.
   [1913 Webster]