USED IN ENTOMOLOGY. 151 



Wing cells: areas inclosed by veins: reference should be had to the figures 

 illustrating venation and to the special terms applied to the cells. 



Winglets: small, concavo-convex scales, generally fringed at tip, under the 

 base of the elytra in Dytiscidee. 



Wing-pads: undeveloped wings of pupa or nymph. 



Wing-scale: in Hymcnoptcra, = tegula; q. v. 



Workers: the undeveloped females in the social Hymcnoptera; also those 

 sexually undeveloped Termites that are not soldiers. 



X 



Xanthophyll: the yellow of autumn leaves; one of the substances found in 



the blood of insects. 

 Xenobiosis: see symbiosis. 



Xerophilous: applied to species living in dry places. 

 Xylophaga: wood-eaters: applied in several orders. 

 Xylophagous: feeding in or upon woody tissue. 

 Xyphus: a spinous or triangular process of the meso-sternum in many 



Hemiptera, and some other insects. 



Yellow: used without modification is sulphur or lemon yellow. 

 Yolk: the nutritive matter of an egg as distinguished from the living, for- 

 mative material ; = deutoplasm. 



Zona: a belt or zone; as of distribution. 



Zonite: = arthromere or somite; q. v. 



Zoonite or Zoonule: = zonite. 



Zygoptera: those Odonata, having the fore and hind wings subequal in width, 



venation comprising a quadrilateral, not a triangle ; nymphs with caudal 



tracheal gills. 



