672 GLOSSARY. 



DicosLous. (Gr.dis; koihs, a cay'ity.) A heart with two cavities. 



DiDACTTLE. (Gr. (lis ; and dactulos, a finger.) A limb terminated by two fingers. 



Digitate. (Lat. digitus, a finger.) When a part sxippoits processes like fingers. 



Dimidiate. (Lat. dimidium, half.) Divided into two halves. 



Dioecious. (Gr. dis, twice, and oikos, a house.) The species which consist of 



male and female individuals. 

 Dimtary. (Gr. dis ; muo7i, a muscle.) A bivalve whose shell is closed by two 



muscles. 

 DiPTERA. (Gr. dis ; pteron, a wing.) The insects which have two wings. 

 Discoid. (Lat. discus, a quoit.) Quoit-shaped. 



Distoma. ({j(\: dis ; stoma, month.') The intestinal worms with two pores. 

 Diverticulum. (From the Latin for a bye-road.) Applied to a bUnd tube 



branching out from the course of a longer one. 

 Dorsad. (Lat. dorsum, the back.) Towards the back. 

 Dorsibranchiate. (Lat. dorsum ; and bragchia, gills.) The Mollusca with gills 



attached to the back. 

 Dorso-intestinal. a part which is on the dorsal aspect of the intestine. 

 Ductus. A duct or tube which conveys away the secretion of a gland. 

 Duodenum. The first portion of the small intestine, which, in the human subject, 



equals the breadth of twelve fingers. 



Ecdtsis. (From the Greek, signifying the act of stripping.) Moulting of the 



skin. 

 Eciiinoderms. (Gr. echinos, a hedgehog ; derma, skin.) The class of radiated 



animals, most of which have spiny skins. 

 Edentulous. From the Latin word for toothless. 

 Edriophthalivia. (Gr. edraios, sitting or sessile ; and ophthalmos, an eye.) The 



Crustacea with sessile eyes. 

 Elytra. (Gr. elutron, a sheath.) The wing sheaths formed by the modified an- 

 terior pair of M'ings of beetles. 

 Emarginate. (Lat. emargino, to remove an edge.) When an edge or margin 



has, as it were, a part bitten out. 

 Emunctories. (Lat. emungo, to wipe the nose.) Parts which carry out of the 



body useless or noxious particles. 

 Enaliosaur. (Gr. enalios, marine ; sauros, a lizard.) An extinct order of marine 



gigantic reptiles allied to crocodiles and fishes. 

 Encephala. (Gr. en, in ; kephale, head.) The molluscous animals which have a 



distinct head. 

 Entomology. (Gr. entoma, insects ; logos, a discourse.) The department of Na- 

 tural History which treats of insects. 

 Entomostraca. (Gr. entoma, insects ; ostracon, a shell.) The order of small 



Crustaceans, many of which are enclosed in an integument, like a bivalve shell. 

 Entozoa. (Gr. entos, within ; zoon, animal.) The animals which exist within 



other animals. 

 Eocene. (Gi\ eos, the dawn ; kainos, recent.) 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. 

 Epiderbial. (Gr. epidermis, the cuticle.) Belonging to the cuticle or scarf-skin. 

 Epimeral. (Gr. epi, upon; meron, a limb.) The part of the segment of an ar- 

 ticulate animal which is above the joint of the limb. 

 Epiploon. (From the Greek.) It is the fatty membrane which covers or occupies 



the interspaces of the entrails in the abdomen. 

 Episternal. (Gr. epi, upon ; sternon, the breast-bone.) The piece of the segment 



of an articulate animal which is immediately above the middle inferior piece or 



sternum. 

 Epithelium. The thin membrane which covers the mucous membranes : it is 



analogous to the epiderm of the skin. 

 Epizoa. (Gr. epi, upon ; zooii, animal.) The class of low organised parasitic 



Crustaceans which live upon other animals, 

 Errantes. (Lat. erro, I wander.) An order of the class Annelida, remarkable 



for their locomotive powers. 

 Excito-motory. The function of the 'nervous system by which an imp'-cssion is 



