GLOSSARY. 487 



Endoderm (Gr. endon ; and derma, skin). The inner integumentary layer of 



the Ccelentei-ata. 

 Endopodite (Gr. endon; and pous, foot). The inner of the two secondary 



joints into which the typical limb of a Crustacean is divided. 

 Endoskeleton (Gr. endon ; and sTceletos, dry). The internal hard structures, 



such as bones, which serve for the attachment of muscles, or the protection 



of organs, and which are not a mere hardening of the integument. 

 Ensiform (Lat. ensis, a sword ; forma, shape). Sword-shaped. 

 Entomophaga (Gr. entoma, insects ; yhago, I eat). Asection of the Marsupialia. 

 Entomosteaca (Gr. entoma, insects ; ostrakon, a shell). Literally Shelled 



Insects ; applied to a division of Crustacea. 

 Entozoa (Gr. entos, within ; zoon, animal). Animals which are parasitic in 



the interior of other animals. 

 Eocene (Gr. eos, dawn ; kainos, new or recent). The lowest division of the 



Tertiary rocks, in which species of existing shells are to a small extent 



represented. 

 Epidermis (Gr. cpi, upon ; derma, the true skin). The outer non-vascular 



layer of the skin, often called the scarf-skin or cuticle. 

 Epimera (Gr. epi, upon ; meron, thigh). The lateral pieces of the dorsal arc 



of the somite of a Crustacean. 

 Epipodia (Gr. epi, upon ; p>'^'^''^, the foot). Musciilar lobes developed from the 



lateral and upper surfaces of the "foot " of some Molluscs. 

 Epipodite (Gr. ejn, upon ; pous, foot). A process developed upon the basal 



joint, or "jirotopodite," of some of the limbs of certain Crustacea. 

 Episterna (Gr. epi, upon ; sternon, the breast-bone). The lateral pieces of 



the inferior or ventral arc of the somite of a Crustacean. 

 Epistome (Gr. epi; and stoma, mouth). A valve-like organ which arches 



over the mouth in certain of the Polyzoa. 

 Epitheca (Gr. epi; and theke, a sheath). A continuous layer surrounding 



the thec?e in some Corals externally. 

 Epizoa (Gr. epi, upon ; zoon, animal). Animals which are parasitic upon 



other animals. In a restricted sense, a division of Crustacea which are 



parasitic upon fishes. 

 Equilateral (Lat. cequus, equal ; latus, . side). Having its sides equal. 



Usually applied to the shells of the Brachiopoda. When applied to the 



spiral shells of the Foram.inifera, it means that all the convolutions of the 



shell lie in the same plane. 

 Equisetace^ (Lat. equus, horse ; seta, bristle). A group of Crypt ogamous 



plants, commonljr known as "Horse-tails." 

 Equivalve (Lat. oeqitus, equal ; valvm, folding-doors). Applied to shells 



which are composed of two equal pieces or valves. 

 Errantia (Lat. erro, I wander). An order of Annelida, often called Nereidea, 



distinguished by their great locomotive powers. 

 Eurypterida (Gr. eurus, broad ; pteron, wing). An extinct sub-order of 



Crustacea. 

 Exopodite (Gr. exo, outside ; p'ous, foot). The outer of the two secondary 



joints into which the typical limb of a Crustacean is divided. 

 Exoskeleton (Gr. exo, outside ; skeletos, dry). The external skeleton, which 



is constituted by a hardening of the integument, and is often called a 



" dermoskeletou." 



