USED IN ENTOMOLOGY. 93 



Orbit: an imaginary border around the eye: in Diptera the orbits are divided 

 into vertical or superior ; frontal and facial or anterior ; of the cheek or 

 inferior ; occipital or posterior. 



Orbital sclerite: a narrow sclerite encircling some eyes. 



Order: one of the primary divisions of the Class Insecta, based largely on 

 wing structure and then usually ending in -ptera. 



Ordure: excrement; usually applied to such as is foul or offensive. 



Orichalceous: = aurichalceous ; q. v. 



Oriental: in geographical zoology as used by Wallace, that part of the earth's 

 surface including Asia east of the Indus River, south of the Himalayas 

 and the Yangtse-kiang watershed, Ceylon, Sumatra, Java and the Philip- 

 pines. 



Orificium: the anal or genital opening. 



Original type: is the actual specimen from which a published description is 

 prepared. 



Orismologia -y: the defining of scientific or technical terms. 



Orthoptera: straight winged: an ordinal term applied to insects in which 

 the primaries are not used in flight, but cover the longitudinally folded 

 secondaries ; mouth mandibulate ; head set into prothorax, the latter free ; 

 metamorphosis incomplete. 



Orthorrhapha: that section of Diptera in which the pupa escapes from larval 

 skin through a T-shaped opening on back : see cyclorrhapha. 



Orthorrhaphous : straight-seamed. 



Os: the mouth of insects, in general. 



Oscillation: a vibrating or swinging from side to side. 



Osculant: intermediate in character between two groups or series. 



Osmaterium -ia: fleshy, tubular, eversible processes producing a penetrating 

 odor, capable of being projected through a slit in the prothoracic segment 

 of certain Papilionid caterpillars, and from openings elsewhere in the 

 bodies of other forms. 



Osmosis: the tendency of liquids to pass or diffuse through a membrane or 

 septum. 



Osselet: = ossicle; q. v. 



Ossicle: a small nodule of chitin resembling a bone. 



Ossicula: small corneous pieces that serve in the articulation of the wings 

 to the thorax. 



Ostia: the slit-like openings of the heart. 



Ostiolar canal: a marginal furrow leading from the ostiole. 



Ostiole: in Hctcroptcra, the openings at the sides of meso- and metathorax, 

 through which an odoriferous fluid is excreted. 



Ostium: singular of ostia; q. v. 



-osus: an affix, signifying saturation, or the possession of the quality ex- 

 pressed in the stem word. 



Otocyst: an auditory or ear-like vesicle. 



Otolith: a little ear-bone: granules or concretions found in an otocyst. 



Outer lobe: of maxilla = galea ; q. v. 



Outer margin: the outer edge of wing, between apex and hind angle. 



Ova, Ovum : the eggs ; an egg. 



