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GLOSSARY. 



special organs for special work, 

 as the specialization of the 

 hand of man from the fore- 

 foot of other mammals ; also 

 applied to the special develop- 

 ment during embryonic life of 

 parts adapted for peculiar or 

 special functions. 



Dig'it. A finger or toe. 



Di-mid'i-ate. Half round. 



Di-ce'ci-ous. (Gr. dis, two; 

 oikon, house). With distinct 

 sexes. 



Dip'te-ra (Gr. dis, two; pteron, 

 wing). Two-winged flies ; an 

 order of insects. 



Di ver-tic'tj-lum. An offshoot 

 from a vessel or from the ali- 

 mentary canal. 



Duct. A tube or passage usu- 

 ally leading from glands. 



Ec-dy'sis (Gr. ekdusis, casting 

 off). The process of casting the 

 skin ; moulting. 



E chin-o-der'ma-ta (Gr. ec7iinos, 

 a hedgehog or urchin ; hence 

 applied to the sea-urchin ; and 

 derma, skin). The fourth sub- 

 kingdom of animals. 



E las mo-bran'chm (Gr. elasma, 

 a strap; bragchia, gill). The 

 sharks and rays. 



E-la'ter. The spring or forked 

 " tail " of Podurans. 



E-ly'tra (Gr. elutron, a sheath). 

 The fore-wings of beetles, 

 serving to cover or sheathe the 

 hind wings. 



Em'bryo. The germ or young 

 animal before leaving the egg 

 or body of the parent. 



Endo blast. The primitive, 

 embryonic endoderm. 



En te-ron (Gr. enteron). A gen- 

 eral term applied to the diges- 

 tive canal as a whole. 



E-phem'e-ri-na. The order of 

 net-veined insects represented 

 by Ephemera. 



E'-pi blast. The ectoderm in 

 its embryo state. The ecto- 

 blast. 



E-pib'o le. Where the gastrula 

 is formed by a spreading of a 

 thin layer of epiblast cells 

 over the much larger hypoblast 

 cells. 



E-pis'to-ma. That part of the 

 face of flies situated between 

 the front and the labrum. 



E qui-lat'e ral. Having the 

 sides equal, as in Brachiopod 

 shells. 



E'qui- valve. Applied to shells 

 like the clams and most La- 

 mellibranchs, which are com- 

 posed of two equal pieces or 

 valves. 



Ex ser'ted. Protruded; opposed 

 to enclosed. 



Ex-u'vi-um. Cast-off skin. 



Fis-sip'a-rous (Lat. fissus, cleft ; 

 pario, to bring forth). Ap- 

 plied to a form of asexual gen- 

 eration where the parent splits 

 into two parts, each part be- 

 coming a new individual. 



Fce'tus. The embryo of a 

 mammal. 



Gang'li-on (Gr. gagglion, a swell- 

 ing or lump). A centre of 

 the nervous system, consisting 

 of nerve-cells and fibres. 



Gem-mip'a-rous (gemma, bud ; 

 pario, to bring forth). Ap- 



