492 NORTH AMERICAN DIPTERA 



Subcostal cell — The cell between the subcosta or auxiliary vein and the first 

 vein or radius. 



Subcostal crossvein — A crossvein, sometimes present, connecting the subcosta 

 or auxiliary vein and the first vein. This is used taxonomically in the 

 Mycetophilidae and the Tipuloidea (Morphologically sc^). 



Subcostal vein — The vein lying between the costa and the first longitudinal 

 vein. It is sometimes absent or greatly reduced. 



Sublateral bristles — Bristles situated in a line with the intra-alars but in front 

 of the suture. The anterior two are sometimes included as posthumerals 

 but the term is deceptive. 



Submarginal cell(s) — The cell or cells lying between the second and third 

 longitudinal veins (R3 and R4). 



Sulcate — Grooved or furrowed. 



Supernumerary cells — Additional cells occurring in the wings due to the 

 presence of extra crossveins (See Nemestrinidas, Bombyliidse, etc.). 



Supernumerary crossveins — Crossveins, other than those normally present. 



Supra-alar bristles — Bristles close to the edge of the thorax behind the suture. 



Suture — A line separating the parts of the body wall. 



Tarsus (si) — The feet, composed normally of five segments. The apical seg- 

 ment bears the claws, pulvilli and empodium when these are not obsolete. 

 In rare cases the number of tarsal segments is reduced to two. The 

 tarsal segments are numbered fi'om the base, segments one to five, al- 

 though the first segment is sometimes termed the basitarsus or meta- 

 tarsus. 



Tegulse — See Squamae. 



Tergites — Dorsal sclerites or the upper side of the segment. 



Third longitudinal vein — The vein arising jointly with the second vein and 

 branching from it, sometimes branched. Behind it is the first posterior 

 cell and behind or before its base, the first basal cell (R4+:, ; Posterior 

 branch of Rs. ; Cubital). 



Thorax — The middle part of the body bearing the wings and legs. 



Tibia(e) — The part of the leg beyond the femur. 



Transverse suture (of thorax) — The depressions extending inward from the 

 sides of the mesonotum near the middle, but not true sutures. In the 

 Muscoids this is said to be complete or extend entirely across, but this is 

 not always the case. Usually the suture is obsolete in the middle. In the 

 Tipulidse it is V-shaped. The suture divides the anterior series of bristles 

 from the posterior dorsocentrals and acrosticals, whether it is complete or 

 not. 



Trichostical bristles — Hypopleural bristles, used especially in the Asilidae. 



Trochanter — The small, ring-like portion connecting the coxae and femora. 

 This often appears more or less triangular as only part of it is generally 

 visible. 



Truncate — Ending transversely or with cut-off apex. 



Tubercle — A conspicuous, more or less rounded swelling, sometimes elongate 

 as on the face of Syrphidse, etc. 



Tuberculate pits — Paired shiny dots at or near the anterior margin of the 

 mesonotum, one on either side of the median line; in Tipulidae. 



Ungues — Claws. 



Venation — The arrangement of the veins of the wings. 



Venter — The under surface of the abdomen. 



Ventrad — Toward the venter. 



Ventral — Pertaining to the under side of the body. 



Vertex — The uppermost edge of the front; usually that part between the 

 ocelli and the back of the head, or behind and between the upper angles 

 of the eyes. 



Vertical triangle — The space, in holoptic flies, surrounding the ocelli. 



