GLOSSARY. 319 



Propolis, — A resinous material collected by the Hive-Bees from the 

 opening buds of various trees. 



Protean. — Exceedingly variable. 



Protozoa. — The lowest great division of the Animal Kingdom. 

 These animals are composed of a gelatinous material, and show 

 scarcely any trace of distinct organs. The Infusoria, Foramini- 

 fera, and Sponges, with some other forms, belong to this 

 division. 



Pupa (pi. Pup^e). — The second stage in the development of an 

 Insect, from which it emerges in the perfect (winged) reproduc- 

 tive form. In most insects the pupal stage is passed in perfect 

 repose. The chrysalis is the pupal state of butterflies. 



Radicle. — The minute root of an embryo plant. 



Ramus. — One half of the lower jaw in the Mammalia. The portion 

 which rises to articulate with the skull is called the ascending 

 ramus. 



Range. — The extent of country over which a plant or animal is 

 naturally spread. Bange in time expresses the distribution of a 

 species or group through the fossiliferous beds of the earth's 

 crust. 



Retina. — The delicate inner coat of the eye, formed by nervous 

 filaments spreading from the optic nerve, and serving for the 

 perception of the impressions produced by light. 



Retrogression. — Backward development. When an animal, as it 

 approaches maturity, becomes less perfectly organised than 

 might be expected from its early stages and known relation- 

 ships, it is said to undergo a retrograde development or meta- 

 morpjJwsis. 



Rhlzopods. — A class of lowly organised animals (Protozoa), having a 

 gelatinous body, the surface of which can be protruded in the 

 form of root-like processes or filaments, which serve for loco- 

 motion and the prehension of food. The most important order 

 is that of the Foraminifera. 



Rodents. — The gnawing Mammalia, such as the Rats, Rabbits, and 

 Squirrels. They are especially characterised by the possession 

 of a single pair of chisel-like cutting teeth in each jaw, between 

 which and the grinding teeth there is a great gap. 



Rubus. — The Bramble Genus. 



Rudimentary. — Very imperfectly developed. 



Ruminants. — The group of Quadrupeds which ruminate or chew 

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