CLASSIFIED HABITATS 433 



61. Terrace : A level plain usually with a steep front, border- 

 ing a river, lake, or sea. 



62. Cave: An underground hollow place, or cavern. 



63. Sand Drift: A tract of drifting sand. 



64. Dune: A hill of drifting sand usually formed on the 

 shore or coast, but often carried far inland by the prevailing 

 winds. 



65. Slope: An incline of land; (a) sun exposed; (b) shaded; 

 (c) wooded. 



66. Ridge: The upper part of a range of hills, or extended 

 elevation between valleys. 



67. Cliff: A high steep rock, a precipice; (a) wet; (b) light; 

 (c) shaded. 



68. Crevice: A narrow opening resulting from a crack or 

 split. 



69. Rock: Natural deposit of earth's crust of a concrete 

 stony material; in this region limestone crops out on the surface; 

 the soils over it: (a) sandy; (6) humus; (c) clay. 



70. Humus : That portion of the soil formed by the decompo- 

 sition of animal and vegetable matter; (a) clay; (6) sandy; 



(c) moist; (d) dry; also under mesophytic condition. 



71. Heath: A tract of land overgrown with shrubs and 

 coarse herbage (dry meadow); (a) border. 



72. Moor: An extensive waste covered with patches of 

 heath and bearing a poor light soil, but sometimes marshy 

 and abounding in peat; (a) atoll. 



73. Snow: Watery particles congealed into white or trans- 

 parent crystals or flakes in the air, and falling to the earth, 

 covering the ground in winter. 



74. Alkali: Soils containing alkali. 



75. Sterile: Unproductive land; (a) dry; (b) sandy; (c) open; 



(d) moist. 



76. INIan's Houses: Country and City Houses; (a) basements; 

 (6) upper floors. 



Note. — These habitats are arranged with reference to water 

 and topography. The primary divisions under this grouping 

 relate to water, forest, grasslands, and desert. These divisions 

 are often further classified as hydrophytes, mesophytes, hylo- 

 phytes, poophytes, and xerophytes, respectively, but I have 

 restricted the classification, giving only the three main divisions. 

 I have omitted regional classification, as being too extensive 

 to enter here, and which can be found well amplified in such 

 works on ecology as those of Schimper and Warming, and in 

 those of Clements. The habitats here referred to are those 

 often mentioned in descriptive books and in the present work. 



