GLOSSARY. 515 



Nbutebs. —Imperfectly developed females of certain social insects 

 (such as Ants and Bees), whicli perform all tlie labors of tlie 

 community. Hence they are also called workers. 



Ocelli. — The simple eyes or stemmata of Insects, usually situated 

 on the crown of the head between the great compound eyes. 



CEsoPH ASUS.— The gullet. 



Oolitic. — A great series of secondary rocks, so called from the 

 texture of some of its members, which appear to be made up of 

 a mass of small egg-like calcareous bodies. 



OPEHCtJLTJM. — A calcareous plate employed by many Mollusca to 

 close the aperture of their shell. The opercular vcHvea of Cirri- 

 pedes are those which close the aperture of the shell. 



Okbit. — The bony cavity for the reception of the eye. 



Organism. — An organized being, whether plant or animal. 



Okthospermous. — A term applied to those fruits of the Umbelliferae 

 which have the seed straight. 



Osculant. — Forms or groups apparently intermediate between and 

 connecting other groups are said to be osculant. 



Ova. — Eggs. 



Ovarium or Ovary (in plants). — The lower part of the pistil or 

 female organ of the flower, containing the ovules or incipient 

 seeds; by growth after the other organs of the flower have 

 fallen, it usually becomes converted into the fruit. 



O viGEROUS. — Egg-bearing. 



Ovules (of plants). — The seeds in the earliest condition. 



Pachyderms. — A group of Mammalia, so called from their thick 



skins, and including the Elephant, Rhinocerous, Hippopotamus, 



etc. 

 Paljeozoic. — The oldest system of fossiliferous rocks. 

 Palpi. — Jointed appendages to some of the organs of the mouth in 



Insects and Crustacea. 

 Papilionace^.— Anorder of Plants (see Leguminos^).— The flowers 



of these plants are called papilionaceous, or butterfly-like, from 



the fancied resemblance of the expanded superior petals to the 



wings of a butterfly. 

 Parasite. — An animal or plant living upon or in, and at the 



expense of, another organism. 

 Parthenogenesis. — The production of living organisms from unim- 



pregnated eggs or seeds. 

 Pedunculated. — Sapported upon a stem or stalk. The peduncu- 

 lated oak has its acorns borne upon a footstool. 

 Peloria or Pelorism. — The appearance of regularity of structure 



in the flowers of plants which normally bear irregular flowers. 

 Pelvis.— The bony arch to which the hind limbs of vertebrate 



animals are articulated. 

 Petals. — The leaves of the corolla, or second circle of organs in a 



flower. They are usually of delicate texture and brightly colored. 

 PhyllODINBOUS. — Having flattened, leaf-like twigs or leaf-stalks 



jnstead of true lejives, 



