150 EXPLANATION OF TERMS 



Viscous: thick, sticky or semi-fluid. 



Vis formatrix: the creative or formative force. 



Vitelligenous: producing the vitellus or yolk: said of certain cells in the 



ovaries, believed to have that function. 



Vitelline -us: yellow, with a slight tinge of red, like yolk of an egg. 

 Vitelline membrane: the delicate tissue surrounding the yolk of an egg. 

 Vitreous: glassy; transparent. 

 Vitta: a longitudinal, colored line. 

 Vitta frontalis: = frontal stripe; q. v. 

 Vittate: striped. 



Viviparous: applied to insects which bear living young. 

 Vocal cords: specialized organs on the thoracic spiracles of Diptera, by 



means of which they produce a humming or singing sound. 

 Volant: flying or capable of flight. 

 Vulgar: common; not conspicuous: obscure in appearance and abundant in 



number. 



Vultus: face: that part of head below front and between the eyes. 

 Vulva: the orifice of the vagina in the female. 



Vulvar lamina: in Odonata, the posterior margin of sternum of segment 8. 

 Vulvar scale: = v. lamina. 



W 



Wart: a spongy excrescence, more or less cylindric, with a nearly truncated 

 tip : the enlarged, common base of a group of setae : in Trichoptera, a 

 pitted elevation. 



Wax: a ductile substance excreted by bees and other insects from glandular 

 structures in various parts of the body, used in building cells or in forming 

 a protective covering. 



Wax-cutter: the pincer-like structure formed by the hind tibia and meta- 

 tarsus in social bees. 



Wax-glands: any glands in any part of the body which secrete a waxy 

 product in either a scale, string or powder : in Coccidce, the circumgenital 

 and parastigmatic glands ; q. v. 



Wax-pincer: = wax cutter. 



Wax-scale: one of the scales secreted in the wax pocket or gland of a 

 worker bee. 



Whitlows: = paronychia ; q. v. 



Whorl: a ring of long hair arranged around a centre, like the spokes around 

 the hub of a wheel. 



Wing, Wings: membranous reticulated organs of flight; one pair, the pri- 

 maries, attached to the meso-thorax; the other, the secondaries, attached 

 to the meta-thorax. 



Wing covers: those parts of the chitinous cuticle of larvae, nymphs or pupae 

 which cover the rudiments of the wings of the imago : the f orewings of 

 an imago when they are thicker than the hind wings and cover them when 

 at rest : see elytra ; tegmina. 



Wings of the heart: the series of diagonal and other muscular fibres above 

 the diaphragm in the pericardial cavity : see pericardial diaphragm. 



