Dufour's gland: that gland, in Hymenoptera, that secretes the alkaline portion of the poison carried by the sting. Duodenum: the chylific ventricle; also applied to the first section of the digestive tract just behind entrance of malpighian tubules. Dupion: a cocoon spun by two silk-worms together; also the coarse silk from such a cocoon. Duplicate -us: double. Duplicate-pectinate: having the branches of a bipectinated antenna alternately long and short. Duple: double, or twice. Durus: hard. Dusky: somewhat darkened; pale fuscous. E E: as prefix, is privative and means without. Ears: organs of hearing, as on the first tibiae or on the first abdominal segment of some Trichoptera. Ebenine: black like ebony. Eburneous: ivory white. Ecalcaratus: without a spur. Ecaudate: without tails or tail-like processes: usually applied to wings : = excaudate. Ecdysis: the process of casting the skin; moulting. Echinate: set with prickles. Ecology: the science of the relation of organisms to each other and to their surroundings: = ethology. {Scanner's comment: Ethology nowadays refers to studies in animal behaviour, not directly to ecology.} Ectad: extending outwardly from within. Ectal: belonging or relating to the outer surface. Ectoblast: the outer wall of a cell; the ectoderm or epiblast. Ectoderm: the outer layer of skin: the outer layer of the blastoderm, giving rise to the nervous system and to epithelial structures of the body surface. Ectognathus: see ectotrophous. Ectoskeletal: referring to the outside or exoskeleton. Ectotrachea: the outer surface or layer of the trachea. Ectotrophous: with mouth parts free; not buried in the head: see entrotrophus. Edematus: dull translucent white. Edentate -ulous: without teeth. Edentula: those having no teeth. Efferent: carrying outward or away from the centre. Effluvium: a foul or unpleasant smell or emanation. Effected: somewhat angularly bent outward. Egg: a simple cell, capable of fertilization, containing the germ, the food-yolk necessary for its nutriment, and a covering membrane: a single ovum or cell from an ovary: the first stage of the insect. Egg-burster: a projecting point on the head or other part of an embryo, used in breaking the shell when hatching. Egg-calyx: the enlarged portion of the oviduct at the opening of the ovarian tubes, into which the egg is received before its entrance into the vagina. Egg-case: the case or covering prepared or secreted by an insect to contain or hold together the egg-mass as a whole: see ooetheca. Egg-guide: Orthoptera; two small pointed prolongations of the ventral portion of the 8th abdominal segment, between upper and lower valves, used in oviposition. Egg-pouch: see ooetheca. Egg-pod: applied to the egg-mass of grasshoppers. Egg-tube: see ovarian tube. Ejaculatory duct: see ductus ejaculatorius. Elastic: a part which has a degree of flexibility throughout. Elate -us: see elevatus.