226 INDEX OF SCIENTIFIC TERMS 



Sternite — chitinous plate on the ventral side of a body segment 

 Sternum — chitinous plate behind the labium, forming the underside of 



the prosoma of an Arachnid 

 Stink gland — repugnatorial gland (q.v.) 

 Stridulation — sound production by the mechanical friction of one part 



of the body against another; usually by means of a number of file-like 



ridges which rub against another set of ridges or a cluster of chitinous 



granules or pegs 

 Systole — contraction of the heart or arteries forcing the blood through 



the system 47 



Tarsus — terminal segment of an arthropodan limb which bears the claws 

 Taxis — direct orientation in response to a stimulus. Cf. Kinesis (q.v.) 

 Tergite — chitinous plate on the dorsal side of a body segment 

 Thigmotaxis — directed response to the stimulus of contact 73 

 Tibia — segment of arthropodan limb between patella and metatarsus 



(q.v.) 

 Toxocognath — maxillipede (q.v.) 

 Tracheae — fine tubes carrying air from the spiracles and branching into 



the tracheoles of most terrestrial arthropods 16, 40, 44, 62, 189, 205 

 Tracheoles — fine tracheal capillaries which conduct air from the tracheae 



to the tissues in most terrestrial arthropods 205 

 Trichobothrium — very fine seta or hair usually believed to have an 



auditory as well as tactile function 75 , 112 

 Tritonymph — third nymphal stage following deutonymph (q-v.) 112 

 Trochanter — the second, ring-like segment of an arthropodan limb 



Uric acid — insoluble excretory compound characteristic of insects 206 

 Uropod — terminal abdominal appendage of Crustacea 8 



Vulva — external reproductive organ, especially the orifice or opening of 

 that organ 31 



