316 ANIMAL LIFE 



Lagoon' : a pool or lake ; the still water inclosed within an atoll. 



Lar'va: 57. 



Lepidbp terous : referring to the Lepidoptera, or moths and butterflies. 



Littoral: 160. 



Lu'men : the cavity of a tubular organ. 44. 



Medusa: 24. 

 Meg alops : 59. 

 Mes'oderm: 20. 



Metab olism: the act or process by which dead food is built up into 

 living matter, and living matter is broken down into simpler prod- 

 ucts within a cell or organism. 



Metamor'phosis : 56. 



Migration: 70. 



Millimeter : about one twenty-fifth of an inch ; a term used in the 

 metric system of measure. 



Mimicry: 112. 



Mind: 140. 



Molt: 57. 



M6n5g'amous : said of animals in which a male mates with only a 

 single female. 



Multiplication: used in the text usually synonymously with repro- 

 duction. 



Myrmecbph ilous : said of insects which are found inhabiting the nests 

 of ants. 



Natural selection: 70. 



No tochord : an elastic rod, or row of cells, formed in the early embryo 

 of chordate animals (including all the vertebrates and some others), 

 which lies below the dorsal nervous tube and above the ventral ali- 

 mentary tube. 



Nucleus (pi. nuclei) : 2. 



CEsoph'agus: 42. 



Olfactory : referring to the sense of smell. 



Oma'sum: 42. 



Organ: 37. 



Organic : referring to the matter of which animals and plants are corn- 



Organism : a living being, plant or animal. 

 Orientation: 95. 

 O'tolith: 121. 



