GLOSSARY. 433 



Denudation. — The wearing away of the surface of the land by water. 



Devonian System or formation. — A series of Palaeozoic rocks, including 

 the Old Red Sandstone. 



Dicotyledons or Dicotyledonous Plants. — A class of plants character- 

 ised by having two seed-leaves, by the formation of new wood between 

 the bark and the old wood (exogenous growth) and by the reticulation 

 of the veins of the leaves. The parts of the flowers are generally iu 

 multiples of five. 



Differentiation. — The separation or discrimination of paits or organs 

 which in simpler forms of life are more or less united. 



Dimorphic. — Having two distinct forms. — Dimorphism is the condition of 

 the appearance of the same species under two dissimilar forms. 



DiceciOUS. — Having the organs of the sexes upon distinct individuals. 



Diorite. — A peculiar form of Greenstone. 



Dorsal. — Of or belonging to the back. 



Edentata. — A peculiar order of Quadrupeds, characterised by the absence 

 of at least the middle incisor (front) teeth in both jaws. {Examples, 

 the Sloths and Armadillos.) 



Elytra. — The hardened fore-wings of Beetles, serving as sheaths for the 

 membranous hind-wings, which constitute the true organs of flight. 



Embryo. — The young animal undergoing development within the egg or 

 womb. 



Embryology. — The study of the development of the embryo. 



Endemic. — Peculiar to a given locality. 



Entomostraca. — A division of the class Crustacea, having all the seg- 

 ments of the body usually distinct, gills attached to the feet or organs 

 of the mouth, and the feet fringed with fine hairs. They are generally 

 of small size. 



Eocene. — The earliest of the three divisions of the Tertiary epoch of geolo- 

 gists. Rocks of this age contain a small proportion of shells identical 

 with species now living. 



Ephemerous Insects. — Insects allied to the May-fly. 



Fauna. — The totality of the animals naturally inhabiting a certain 

 country or region, or which have lived during a given geological 

 period. 



Felidje.— The Cat-family. 



Feral. — Having become wild from a state of cultivation or domestication. 



Flora. — The totality of the plants growing naturally in a country, or 

 during a given geological period. 



Florets. — Flowers imperfectly developed in some respects, and collected 

 into a dense spike or head, as in the Grasses, the Dandelion, &c. 



Fcetal. — Of or belonging t j the fcetus, or embyro in course of develop- 

 ment. 



Foraminifera. — A class of animals of very low organisation, and generally 

 of small size, having a jelly-like body, from the surface of which deli- 

 cate filaments can be given off and retracted for the prehension of 

 external objects, and having a calcareous or sandy shell, usually 

 divided into chambers, and perforated with small apertures. 



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