Any of the primitive insects which have never developed wings during their history- bristletails.

 organ for sucking liquids. Hemelytron:   

     pupa in which the appendages are fixed to the rest of body-butterfly chrysalis. Occipital Suture:

 auditory membrane in certain insects.  

     seen only in Odonata on sternites of second and third abdominal segments.

     an acetyl ester of choline involved in the synaptic transmission between nerve cells.

     enzyme within the synaptic gap that hydrolyses acetylcholine to choline and acetic acid.

     pointed, needle shaped.

     flexible setae fringed nozzle in formicine ants.