Selva 



An equatorial Rain forest in the Amazon River basin in 

 South America. 



Sematic 



Refers to an organ, odor, color, or other attribute of an 

 animal that may serve as a warning to other animals. 



Semiarid 



Refers to a region or climate that is intermediate between 

 Arid and Subhumid, with Precipitation-effectiveness ratios 

 ranging between 16 and 32, and supporting grassland or 

 shrub types of vegetation. 



Seminal 



Refers to seed or semen. 



Seminatura! Community (Vegetation) 



A community in which the development or character- 

 istics have been modified in part by man's influence, e.g., 

 a successional community on an area where sagebrush was 

 burned by man. 



Semipermeable 



Refers to a membrane that permits certain substances 

 to pass through readily while others pass through slowly or 

 not at all; differentially permeable. 



Senescence 



The process of aging. 



Senility 



The state of old age. 



Sensory 



Refers to the capacity or sense-organ of an animal by 

 which it receives stimuli. 



Sepal 



See Calyx. 



307 



