The Collaborative International Dictionary
Nemathecia
Nemathecium \Nem`a*the"ci*um\ (? or ?), n.; pl. Nemathecia. [NL., fr. Gr. nh^ma a thread + ? a box.] (Bot.) A peculiar kind of fructification on certain red alg[ae], consisting of an external mass of filaments at length separating into tetraspores.
Wiktionary
nemathecia
n. (plural of nemathecium English)