NO. 1687. THE THORAX OF INSECTS— SNODGRASS. 581 



Steimellimi {/SI).- — The third division of the sternum. Sternellvni 

 MacLea}'^ (1830), Comstock and Kochi 1002. Poststertium Amans 

 (1885)/ 



Stemites {Ps, S, SI). — All the sclerites of any sternum. (Gen-' 

 erally used as synonymous with steriia.) 



Sternum {S). — The entire ventral surface of any segment corre- 

 sponding with the tcrgu'in., or also, specifically, the principal or sec- 

 ond sternal sclerite. Sternum Audouin (1824). 



Suhcosta (So). — The second principal vein of the wing, associated 

 at its base with the first axillary. 



Suprae pimerum. — A dorsal subdivision of the epimerum in the 

 meso- and metathorax of Coleoptera (epm), often entirely separated 

 in the metathorax. Parapleure Kolbe (1889), Postparapterum 

 Snodgrass (1908). 



Tarsus. — The foot of insects, composed of five, or fewer, small 

 joints, the last bearing the claws. Tarsvs Fabricius (1778) Manus of 

 front leg, tarsus of middle and hind legs, Kirby and Spence (182G). 



Tegula {T<j). — -The scale-like plate overlapping the front angle 

 of the base of the v;ing in Lepidoptera, Hymenoptera, and Diptera, 

 and its pad-like representative at the base of the wing in other orders. 

 The tegular of the front wings of Lepidoptera are specially large and 

 are carried by special tegular plates {tg) of the notum. These, in 

 turn, are supported by special internal tegular arms {tg A) from the 

 bases of the pleural wing processes. Cuilleron 3\\y\x\q (1820). Teg- 

 ula Kirby and Spence (1826). Parapteron MacLeay (1830). 



Tergites {Pse, Set, Sci, PN). — The sclerites composing the tergum 

 of any segment. (Generally used as synonomous with terga.) 



Tergum {T). — The entire chitinization of the dorsum of any seg- 

 ment. (See Notum and Pseud onotum.) Tergum Audouin (1824), 

 MacLeay ( 1830) . Notum Burmeister ( 1832) , Newport ( 1839 ) . Pro- 

 thorax., mesotJiorax and metathorax (thoracic terga) Kirby and 

 Spence (1826). Bouchier (protergum), ecusson (mesotergum), 

 elypeus and tergum (metatergum) Straus-Diirckheim (1828). 



Third axillary (J, 3 Ax.^ longitudinal .shading). — The sclerite of 

 the wing base associated with the bases of the anal veins and afford- 

 ing insertion for the muscles which fold the anal area of the wing. 

 Anteriorly it articulates with a process of the second axillary, and 

 mesally with the posterior notal wing process except when the fourth 

 axillary is present, which intervenes between the third and the wing 

 process. The muscle insertion is on the mesal side of the axis of the 

 sclerite so that by its contraction the sclerite revolves and folds the 

 attached anal part of the wing. Petit cuhital of front wing, fourchu 

 of hind wing, Jurine (1820). Onguiculus Chabrier (1820). Epau- 

 liere posterieure of elytrum, quatrieme axillaire of hind wing, Straus- 

 Diirckheim (1828). Terminal Am2iY)& (1885), Petri (1899). Meta- 



