429 



Dor'sal vessel, in insects, 359. 



Dorsibranchia'ta (Lat. dot-sum, the j 

 back : Gr. ftpayxia, g' lls ) mo1 - 

 lusks with gills attached to the 

 back, xxii. 



Drift formation, 650, 684. 



Duc'tus (Latin), a duct, or tube, 

 which conveys away the secretion 

 of a gland. 



Duode'num (Lat. duodecim, twelve), 

 the first portion of the small in- 

 testine, which in the human sub- 

 ject equals the breadth of twelve 

 fingers. 



Du^ra ma x ter, 85. 



E, Ex, a Latin prefix, signifying 

 generally "without," or "from," 

 as Edentata, Exosmose; which see. 



Ear, the, 145161. 



Earth's crust, structure of the, 642 

 655. 



Echinas'ter sanguin'olentus, meta- 

 morphoses of the, 557, 558. 



Ech'ini,anorderofEchinoderms,xxiii. 



Echin'oderms (Gr. i%ivo, a hedge- 

 hog ; C|0jua, skin), the class of | 

 radiated animals, most of which 

 have spiny skins, xxiii. 



Echin'oderms, 661 ; internal organs 

 of the, 316 ; jaws of the, 335. 



Eden'tata (Lat. ex, without, dens, a 

 tooth), a class of mammals, in 

 which the teeth are in some degree 

 incomplete ; as in the armadillo. 



Eden'tulous, from the Latin word 

 for toothless. 



Egg, the, all animals produced from, 

 433, 434 ; form, 435 ; formation, 

 436 446 ; development of the 

 young, 447 479 ; structure as 

 just laid, 480 ; changes in, during 

 incubation, 499. 



Elementary structure of organized 

 bodies, 35 ; of tissue, 56. 



El'ytra (Gr. {\vrpov, a sheath), the 

 wing sheaths formed by the mo- 

 dified anterior pair of wings of 

 beetles. 



Emar'ginate (Lat. emargmo, to re- 

 move an edge), when an edge or 

 margin has, as it were, a part bit- 

 ten out. 



Em'bryo (Latin), the earliest stage 

 of the young animal before birtii, 

 433. 



Embryol'ogy, 429509 ; the eg?, 

 429 446 ; development of the 

 young, 447 499 ; zoological im- 

 portance of embryology, 500 

 509. 



Enal'iosaur (Gr. eva\to, marine ; 

 cravpr>, a lizard), an extinct order 

 of marine gigantic reptiles allied 

 to crocodiles and fishes. 



Enceph'ala(Gr.6i/,in; KtQaXr), head), 

 molluscous animals which have a 

 distinct head. 



Endogenous, increasing by inward 

 addition, as the palrn tree, 72. 



Endosmose' and exosmose\411,413. 



Entomol'ogy (Gr. tvrojua, insects ; 

 A6yo, a discourse), the depart- 

 ment of natural history which 

 treats of insects. 



Entomos'tracans (Gr. tvrojua, in- 

 sect ; ocrrpaKov, shell), small crus- 

 taceans, many of which are en- 

 closed in an integument, like a 

 bivalve shell, xxii. 



Entozo v a (Gr. fi/roe, within ; Z,a>ov, 

 animal), animals which exist with- 

 in other animals. 



Eocene' (Gr. IM, the dawn ; KCIIVOC, 

 recent), the stage of the tertiary 

 period, in which the extremely 

 small proportion of living species 

 indicates the first commencement 

 or dawn of the existing state of 

 animate creation, 650. 



Epider'mal (Gr. eTridep/^i^, the cuti- 

 cle), belonging to the cuticle or 

 scarf skin, 413. 



Epister'nal (Gr. era, upon ; arepvov, 

 the breast-bone), the piece of the 

 segment of an articulate- animal 

 which is immediately above the 

 middle inferior piece, or sternum. 



