GLOSSARY 



499 



Cuticle, an elastic exoskeleton of horny con- 

 sistency external to the epidermis, by which 

 it is secreted. 



Cysticercus, pi. -i (Gk. cysHs, a bladder; 

 k^rkfiSy a tail), in most Tape- Worms, the 

 bladder-worm stage. 



Darwinism. See Natural selection. 



Degeneration, a process of simplification 

 whereby some forms adapt themselves to a 

 parasitic or to a fixed mode of Ufe. 



Denitrifying, used of bacteria which liberate 

 nitrogen from organic matter. 



Dental formula, a numerical expression, show- 

 ing the number and kinds of teeth present in 

 a given species of Mammal. 



Dentine (L. dens^ dentisy a tooth), a hard sub- 

 stance of which teeth are chiefly composed. 



Dermatoptic vision (Gk. d^rma, -atos, a skin; 

 optikt^Sy pertaining to sight), seeing by means 

 of the skin. 



Dermis (Gk. d^rma^ a skin), the inner layer of 

 the skin. 



Diaphragm {the Greek name), the midriff. 



Didactyle (Gk. di-^ two; daktyluSy a finger 

 or toe), possessing two digits. 



Digitigrade (L. digitus, the toe of an animal; 

 gradOy I walk), walking upon the digits. 



Diphycercal (Gk. diphyes, double; k^rkuSy a 

 tail). See Protocercal. 



Diploblastic (Gk. diplous, double; blastos, a 

 germ), applied to animals in which the body 

 is essentially composed of two cellular 

 layers. 



Dispersal, the spreading of a species from the 

 area where it was first evolved. 



Dorsal (L. dorsum^ the back), applied to the 

 upper side of an animal. 



Ductless glands, a name applied to a number 

 of small structures, of various use, which do 

 not possess ducts or tubes for carrying off 

 a liquid secretion. See Lymphatic glands^ 

 ThymuSy Thyroidy Spleen. 



Ectoderm (Gk. ^kt^Sy outside; d'^rma, a skin), 

 the external cellular layer of the body. 



Ectoparasite. See Parasite. 



Eder-fold, one of the nesting-grounds of the 

 eider-duck. 



Efferent branchial vessels (L. effSrOy I carry 

 from; Gk. hranchiay gills), blood-vessels 

 w^hich carry off purified blood from gills. 



Efferent nerve-fibre (L. effero, I carry from), 

 a nerve-fibre in which the impulse travels 

 outwards from the central organs. 



Elevage, in French oyster-culture, the rearing 

 of young oysters to a marketable size. 



Eleveur, a French oyster-culturalist concerned 

 with elevage. 



Elytron, pi. -a, (Greek name for (i) ): (i) in 

 Insects, a fore-wing modified into a hard 

 cover for the delicate hind-wing; (2) in 

 some marine Bristle -Worms, a breathing- 

 scale. 



Embryology (Gk. ^mhryYyriy an embryo; Wgtlsy 

 a discourse), the study of the development 

 of animals. 



Endoderm (Gk. ^ndon, within ; d^rmti, a skin), 

 the internal cellular layer of the body. 



Endoparasite. See Parasite. 



Endoskeleton, internal hard parts serving for 

 support, &c. 



Entomophilous(Gk. ^ntYjmos, an insect; philed, 

 I love), of flowers, pollinated by insects. 



Environment, the sum total of an animal's 

 surroundings. 



Eozoic epoch (Gk. eos, dawn; zoe, life), the 

 most ancient geological era. 



Ephippium (Gk. ^phippio)iy a saddle-cloth), in 

 Water-" Fleas ", a saddle-shaped thicken- 

 ing of the parent-shell, serving to enclose 

 and protect the winter-eggs. 



Ephyra, pi. -se, a young jelly-fish of flattened 

 form, produced by transverse fission of a 

 fixed Zooph^'te. 



Epidermis (the Greek name), the protective 

 outer layer of the skin. 



Epigenesis (Gk. ^pi, after ; geyuiaiiy I pro- 

 duce), the accepted view that development 

 of animals is a process involving a gradual 

 up-building from simple to complex. See 

 Preformation. 



Epiglottis (the Greek name), in Mammals, an 

 elastic flap which prevents food from enter- 

 ing the \vind-pipe. 



Epipodium, pi. -ia (Gk. epiy upon; poiiSy 

 pudoSy a foot), in some Molluscs, a muscular 

 flap arising high up either side of the foot. 



Epipubic, connected with the front end of the 

 Pubis (which see). 



Epithelium, pi. -a, layers of cells covering ex- 

 ternal and lining internal surfaces. 



Ethiopian region, south Arabia with Africa 

 south of the Sahara. 



Euglenoid movement, a wriggling mode of 

 creeping effected by altering the shape of the 

 body, as in Euglena, a sort of Animalcule. 



Eustachian tube, a passage connecting the 

 drum of the ear with the pharynx in air- 

 breathing V'^ertebrates. 



Evolution (L. evolntio, an unfolding), the de- 

 velopment of species by modification of pre- 

 existing species. See also Special creation. 



Excretion, the getting rid of waste products. 



Exhalent. See Siphon. 



Exoskeleton, external hard parts serving for 

 support, &.C. 



Extensor, applied to muscles which straighten 

 or extend a limb, or region of the body. 



Fascine, in oyster-culture, a bundle of twigs 

 used as a spat-collector. 



Femoral, relating to the thigh. 



Femur (L. for thigh): (i) the thigh-bone of 

 Vertebrates; (2) a part of the leg in Insects, 

 &c. 



Fenestra ovalis (L. for oval window), In Verte- 

 brates, a membrane -filled vacuity in the 



