67 Ell 



Ectoderm, or Epiblast. — An outer layer of cells 

 formed by the surface cells overgrowing the 

 open edges of the invagination of the blastoderm. 

 (Gr. ehos, outside, and derma, skin.) See 

 Endoderm. 



Ectotrachea. — The outer or peritoneal membrane 

 covering the tracheae. (Gr. eUos, outside, and 

 trachea.) 



Edentate. — ^Without teeth. (L. edentatus, tooth- 

 less.) 



Edentulous. — Destitute of teeth. (L. edentatus.) 



Edge. — The Margin. (L. acies, edge.) See Acies. 



Egg. — Ovum. (Icel. egg. A.S. ceg.) 



Egg-guide. — The moveable, triangular plate which 

 bounds the oviduct on the ventral side ; especi- 

 ally seen in Acrydiidae. (egg, and F. guider, to 

 guide.) 



Ejaculatory duct {Ductus ejaculatorius).—The duct 

 which ejects the spermatozoa, formed by the 

 two sperm cells joining to form the tube. (L. e 

 and jacio, jactum, to throw, and ductuni, to 

 lead.) 



Elastes. — The elastic organs on ihe ventral seg- 

 ments which assist in the act of leaping. (Gr. 

 elao, elaso, to drive or urge.) 



Elevators. — Wing muscles, attached to the lower 

 region of the thorax-wall, and fixed to the wing- 

 root inside the fulcrum. (L. e, and levo, to rise, 

 from levis, light.) 



EUipticum. — Elliptical in surface shape. (Gr. 

 elleifsis. ) 



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