GLOSSARY. 797 



zob'n ; the opposite, or "proximal," extremity growing less rapidly, and 

 being the end by which the organism is fixed, when attached at all. 



DIURNAL (Lat. dies, day). Applied to animals which are active during the day. 



DrvERTicuLUM (Lat. diverticulum, a by-road). A lateral tube with a blind 

 extremity springing from the side of another tube. 



DORSAL (Lat. dorsum, back). Connected with the back. 



DORSIBRANCHIATE (Lat. dorsum, the back ; Gr. bragchia, gill). Having ex- 

 ternal gills attached to the back ; applied to certain Annelides and Molluscs. 

 The term is of mongrel composition, and " notobranchiate " is more correctly 

 employed. 



ECDERON (Gr. ek, out ; deros, skin). The outer plane of growth of the externa 

 integumentary layer (viz., the ectoderm, or epidermis). 



ECDYSIS (Gr. ekdusis, a stripping off). A shedding or moulting of the skin. 



ECHINOCOCCI (Gr. echinos, a hedgehog ; kokkos, a berry). The larval forms 

 (scolices) of the tapeworm of the dog (Tcenia echinococcus), commonly known 

 as "hydatids." 



ECHINODERMATA (Gr. echinos ; and derma, skin). A class of animals compris- 

 ing the Sea-urchins, Star-fishes, and others, most of which have spiny skins. 



ECHINOIDEA (Gr. echinos; and eidos, form). An order of chinodermata, com- 

 prising the Sea-urchins. 



ECHINOP2EDIUM (Gr. echinos, a hedgehog ; paidion, a child). A term applied 

 to the embryo or larva of the Echinodermata. 



ECHINULATE. Possessing spines. 



ECTOCYST (Gr. ektos, outside ; kustis, a bladder). The external investment of 

 the C03no3cium of a Polyzoon. 



ECTODERM (Gr. ektos; and derma, skin). The external integumentary layer 

 of the Ccelenterata. 



ECTOSARC (Gr. ektos; sarx, flesh). The outer transparent sarcode - layer of 

 certain Rhizopods, such as the Amoeba. 



EDENTATA (Lat. e, without ; dens, tooth). An order of Mammalia, often called 

 JBruta. 



EDENTULOUS. Toothless; without any dental apparatus. Applied to the 

 mouth of any animal, or to the hinge of the bivalve Molluscs. 



EDRIOPHTHALMATA (Gr. hedraios, sitting ; ophthalmos, eye). The division of 

 Crustacea in which the eyes are sessile, and are not supported upon stalks. 



ELASMOBRANCHII (Gr. elasma, a plate ; bragchia, gill). An order of Fishes, 

 including the Sharks and Kays. 



ELYTRA (Gr. elutron, a sheath). The chitinous anterior pair of wings in 

 Beetles, which form cases for the posterior membranous wings. Also ap- 

 plied to the scales or plates on the back of the Sea-mouse (Aphrodite). 



EMBRYO (Gr. en, in; bruo, I swell). The earliest stage at which the young 

 animal is recognisable in the impregnated ovum. 



ENALIOSAURIA (Gr. enalios, marine ; saura, lizard). Sometimes employed as 

 a common term to designate the extinct Reptilian orders of the Ichthyosauria 

 and Plesiosauria. 



ENCEPHALON (Gr. egkepfutlos, brain). The portion of the cerebro-spinal ner- 

 vous axis contained within the cranium. 



ENCEPHALOUS (Gr. en, in ; kephale, the head). Possessing a distinct head. 

 Usually applied to all the Mollusca proper, except the Lamellibranchiata. 



ENCYSTATION (Gr. en, in ; kustis, a bag). The transformation undergone by 

 certain of the Protozoa, when they become motionless, and surround them- 

 selves by a thick coating or cyst. 



ENDERON (Gr. en, in ; deros, skin). The inner plane of growth of the outer 

 integumentary layer (viz., the ectoderm or epidermis). 



ENDOCYST (Gr. endon, within ; kustis, a bag). The inner membrane or integu- 

 mentary layer of a Polyzoon. In Cristatella, where there is no " ectocyst," 

 the endocyst constitutes the entire integument. 



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

 the Ccelenterata. 



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

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



