88 EXPLANATION OF TERMS 



Nervulation: arrangement of the nerves: specifically applied to the arrange- 

 ment of the chitinous framework of wings and thus = venation ; q. v. 



Nervules or Nervures: the rod or vein-like structures supporting the mem- 

 branes of wings and = veins and veinlets ; q. v. 



Nervuration: =nervulation and venation; q. v. 



Neural canal: an incomplete tunnel on the floor of meso- and metathorax, 

 formed by fusion of apodemes, serving for the reception and protection of 

 the ventral nerve cord and for the attachment of muscles. 



Neural groove: is that furrow in the primitive layer of the embryo in which 

 the nerve cord is formed. 



Neuration: = venation ; q. v. 



Neurilemma: the external sheath of a nerve fibre. 



Neuroblast: the large cell in the early embryo, from which the nervous 

 system develops. 



Neuromere: that part of a body segment pertaining to the nervous system. 



Neuroptera: nerve-winged: an ordinal term applied to insects with four net- 

 veined wings ; mouth mandibulate ; head free ; thorax loosely agglutinated ; 

 metamorphosis complete : in its older use, the term applied to all net-veined 

 insects irrespective of metamorphosis or thoracic structure. 



Neuropteroidea: like the Neuroptera in the wide sense; applied to those 

 living insects included by Linnreus in his Neuroptera; also to those extinct 

 forms which have a general resemblance to them. 



Neurospongium: a granular matrix in the periopticon of the insect eye. 



Neuter: the term applied to workers or undeveloped females in some Hy- 

 menoptcra: indicated by 9 or g, an impertect form of Venus sign. 



Nidificate: to nest: applied when eggs are placed in a prepared receptaculum. 



Niger: black. 



Nigricans: black, tinged with gray. 



Nits: the eggs of sucking lice; specifically when attached to a hair: in 

 general, though rarely, applied in the singular to an egg. 



Nitidus: shining: applied to a highly polished, smooth surface. 



Niveous -eus: snowy white. 



Nocturnal: species that fly or are active at night. 



Nodal furrow: in Odonata; a transverse suture, beginning at a point in 

 costal margin corresponding to the nodus, and extending toward inner 

 margin. 



Nodal sector: in Odonata; = media 2 (Comst.) : arises from upper sector 

 of arculus near nodus and extends to outer margin. 



Node: a knot or knob: in the plural refers to the small segment or segments 

 between thorax and main portion of abdomen in ants. 



Nodiform: in the form of a knot or knob. 



Nodicorn: with antennae that have the apex of each joint swollen. 



Nodose -us: knotted or with knots; a body with one or more knotted parts; 

 a sculpture with almost isolated knots. 



Nodule: a little knot, lump or node. 



Nodulose -us -ate: with small nodes or nodules: a surface sculpture of knots 



or links, connected by an undulating line. 



Nodus: in Odonata; a stout, oblique, short vein at the place where the an- 

 terior margin of the wings is sometimes drawn in. 



