=Em´bry-o= [Gr. _en_, in; _bruein_, swell.] The term applied to an animal in the earlier stages of development. =Em-bry-ol´o-gy= [Gr. _embryon_, embryo; _logos_, < _lego_, speak.] The study of embryos. =En´do-derm= [Gr. _endon_, within; _derma_, skin.] =En´do-plasm= [Gr. _endon_, within; _plasso_, form.] =En-ter-op-neus´ta= [Gr. _enteron_, intestine; _pneustos_, breathing.] Acorn-tongue worms. Smooth-bodied, footless worms, having a large exserted soft proboscis; breathing by a series of respiratory sacs opening into the digestive canal, and communicating externally by spiracles; nervous system situated above a seeming notochord. Balanoglossus. Included by some biologists among the chordata. =E-o-hip´pus= [Gr. _eos_. dawn; _hippos_, horse.] =E´o-cene= [Gr. _eos_, dawn; _kainos_, recent.] =Ep-en-ceph´a-lon= [Gr. _epi_, upon; _enkephalos_, brain.] A fundamental subdivision of the brain (encephalon). =Ep´i-blast= [Gr. _epi_, upon; _blastos_, bud.] =E´quus= [Lat. horse.] =E-ryth-ro-lam´prus= [Gr. _erythros_, red; _lampros_, shining.] =Eu-ca-lyp´tus= [Gr. _eu_, good; _kalypto_, cover.] A large genus of evergreen trees of the myrtle family. =Ev-o-lu´tion= [Lat. _e_, out; _volvo_, roll.] =Ex-o-skel´e-ton= [Gr. _exo_, outside; _skeleton_, dried body.] External skeleton; bony or horny hardening of the integument. =Fla-gel´lum= [Lat., dim. of _flagrum_, scourge.] A slender protoplasmic extension of a cell, for purposes of locomotion. =Fo-ram-i-nif´e-ra= [Lat. _foramen_, opening; _fero_, bear.] A division of protozoans secreting a shell perforated by many minute apertures. =Fos´sil= [Lat. _fodio_, dig.] Any organic body so situated in the earth, and so buried in solid rock or in earthy deposits, as to be capable of indefinite preservation. =Gan´gli-on= [Gr. _ganglion_, tumor.] A swelling that consists of an aggregation of nerve-cells. It receives and discharges nervous impulses and serves to stimulate psychical and organic activities. =Ga-noi´de-i= [Gr. _ganos_, brightness; _eidos_, appearance.] =Gas-ter-op´o-da= [Gr. _gaster_, stomach; _pous_, foot.] Including all snails and slugs. =Gas´tru-la= [Dim. of Lat. _gaster_, stomach.] =Gem´mæ= [Lat. buds.] =Geph-y-re´a= [Gr. _gephyra_, bridge.] A division of worms with an œsophageal nervous ring and ventral chord; no distinct segments or legs; a terminal or dorsal anus. =Go´ni-a-tites= [Gr. _gonia_, corner; _lithos_, stone.] A genus of fossil Ammonites. =Gor´gets= [Fr. _gorgette_, dim. of _gorge_, throat.] Throat-patches distinguished by color or texture, especially in humming birds. =Grap´to-lites= [Gr. _graptos_, written; _lithos_, stone.] Fossil hydroids. =Greg-a-ri´na= [Lat. _gregarius_, < _grex_, flock.] A genus typical of Gregarinidæ. _Gregarina gigantea_ is sixteen millimeters in length and is one of the largest unicellular animals known.