137 Nig 



Nervi oculorum. — The optic nerves. They 

 originate from the lateral margins of the 

 hemispheres of the cerebrum, and extend to the 

 orbits, becoming gradually clavate, where they 

 radiate into many branches. (Burmeister.) 

 (L.) 



Nervi optici secundarii. — The auxilliary optic nerves. 

 They are peculiar only to insects possessing 

 stemmata, and originate from the central portion 

 of the cerebrum, and extend as simple and very 

 fine filaments to the spot where the stemmata 

 are situated, and then gradually diverge from 

 each other. (Burmeister.) (L.) 



Nervous System.— [See Cerebral ganglion.] 



Nervures, or Nerves {Nervi.) — (Wing.) Corneous 

 tubes for expanding the wing, and keeping it 

 tense. (L. nervus, from Gr. neuron, a 

 sinew, a chord.) 



Neurilemma. — The hardish sheath formed of cells 

 and miclei covering the ganglii. (Gr. neuron, 

 and lemma, a husk, or rind.) 



Neuroptera. — A family of Hexapoda. An order of 

 insects havingfovir transparent, finely reticulated, 

 membranous wings. (Gr. neuron, a nerve, 

 and fteron, a wing.) 



Nictitant ocelhis. — When the eye of colour includes 

 a lunar spot of a different colour. (From L. 

 nicto, to wink, and oculus, an eye.) 



Niger. — The colour of lamp-black. (L. black.) 



