140 



EXPLANATION OF TERMS 



Thoracic dorsal bristles: in Diptera, the specialized bristles on the dorsum of 

 the thorax. 



Thoracic feet: the jointed legs on the thoracic segments of larvae, as distin- 

 guished from abdominal or pro-legs. 



Thoracico-abdominal: the first segment of the abdomen when united with the 

 thora.x so as to form part of it : = propodeum. 



Thoracic pleural bristles: in Diptera, the speciaHzed bristles situated on the 

 pleural region of the thorax. 



Thoracotheca: ^ cytotheca ; q. v. 



Thorax: the second or intermediate region of the insect body, bearing the 

 true legs and wings : made up of three rings, named in order, pro-, meso-, 

 and meta-thorax : when the pro-thorax is free as in Coleoptera, Orthoptera, 

 and Hemiptera, the term thorax is commonly used in descriptive work for 

 that segment only: in Odonata, where the prothorax is small and not fused 

 with the larger and united meso- and meta-thorax, the term thorax is com- 

 monly used for these latter two united, excluding the prothorax. 



Thread-plate: an epithelial plate of the embryo from which the terminal 

 threads of the ovarian tubes originate. 



Thyridial cell: in Trichoptera ; the cell formed by the first fork of median 

 vein ; the cell behind Thyridium. 



Thyridiate: applied to a wing vein that at one point seems broken so as to 

 permit of a folding or bending ; either to pack into a small compass or to 

 enfold the body. 



Thyridium -11 : small, whitish or almost transparent spots near the anasto- 

 mosis of the disc of the wings in some Nenroptera ; or in the recurrent 

 veins in the cubital cellule in some Hymenoptera ; also the apical margin of 

 the gastrocceli, often alone visible : in Trichoptera, specifically, a hyaline spot 

 on second fork of median vein. 



Thyrsus: a cluster. 



Thysanoptera: fringe-winged: an ordinal term, applied to species with four 

 narrow, similar wings, lengthily fringed ; mouth parts fitted for puncturing 

 and scraping ; metamorphosis incomplete : the Thripids. 



Thysanura: fringe-tails: wingless, mandibulate insects without metamorphosis; 

 with anal appendages ; body covered with scales ; thoracic segments similar. 



Tiarate-us: turban or tiara-like. 



Tibia -ae: the shank: that part of the leg articulated to the femur basally and 

 which bears the tarsus at the distal end. 



Tibial epiphysis: a movable process attached near the base of the inner side 

 of the anterior tibia in many Lepidoptera. 



Tibial membrane: in J' Cicada, the drum-like vibratory membrane that pro- 

 duces the sound. 



Tip: the extremity; the part furthest removed from the base. 



Titlllator: a small piccess just below the penis in some Orthoptera. 



Tomentose: covered with fine hair, so matted together that particular hairs 

 cannot be separated 



Tomentum: a form of pubescence composed of matted, woolly hair: in 

 Diptera applied to a covering of short, flattened, more or less recumbent, 

 scale-like hair which merges gradually into dust or pollen. 



