GLOSSARY. XIX 



Jt(K</nim, or ^iioiil. — Tlie usual, more or less cylindrical, anterior prolongation 

 of the head that projects over the proboscis proper, most conspicuous 

 (amongst the JS'e.matoceka) in Tipui.idj;. Probably some of the older 

 authors used the term to include both the rustriun proper and the 



proboscis also. 



&t/pe, or scapiis. — The first two (or basal) joints of the antenna;, nearly always 

 diftereutiated from the rest. In the Nematoceua, the 2nd joint is 

 generally much shorter tiian the 1st, and the 1st joint of the flagellum 

 (/. e., the remaining joints taken together) is usually longer than the 

 others. The scape is in nearly all cases sufficiently obvious. 



JScKtellai- ridge. — A sometimes very conspicuous hai-dened ridge joining the 

 sides of the scutellum t(j the thorax. Often inconspicuous or absent. 

 Loew has suggested for it the name " frenulum." 



ScideUum. — The semicircular or crescent-shaped small piece affixed to the 

 hinder margin of the thoracic dorsum. It often bears important bristles 

 or spines, though less frequently so in the Nematocera than in some 

 other groups. 



Seta. — Applii'd to a somewhat long bristle-like bair. It is also used to 

 designate the microscopic stiff hairs with which many wings are covered, 

 and which are invisible to the naked eye. 

 • Scdgcrous. — Provided with seta;. 



Spiirmis cell.^See p. 15. 



Sgiiama. — The most correct teriu for the scale-like organs (one covering 

 the other, either equal in size or tiie lower one nuich larger than the 

 upper) found at the root of the wings iu the higher Diptera. The 

 upper or anterior one is fixed to the base of the wing behind the alula 

 and is most correctly termed the alar squama or squama alaris; the 

 hinder or posterior one, which in all the higher groups of Muscid^e and 

 other families is always much larger than its companion, is attached to 

 the thorax and is therefore most correctly called the thoracic squama or 

 squama thoracis or thoracicalis. The presence or absence of these organs 

 gives the distinguishing names of Calyi'trata and Acalvptkata, dividing 

 the MusciD.E (scnsu laio) into two great groups, above subfamilies and 

 approximately of equal extent. The line of demarcation, however, is 

 not absolute, many small ANTiiOMYiDyE having squaraas of equal size and 

 very little larger than those found in the Acalyptrata, in which group, 

 moreover, exceptions with squauise of comparatively large size are louud. 

 Some authors call them tegulw, calypters, or (erroneously) alulaj. 



Stcrnopleura. — The pleural area forming the lowest part of the ventral surface 

 of the thorax, developed chiefly between the fore and middle pair of 

 legs. 



Sternum. — The lower surface of the thorax. 



Sternitcs. — The plates on the lower surface on the body of au insect, but here 

 specially used to denote the ventral plates of the abdominal segments, 

 the numbers of which are counted from the base outwards ; opposed to 

 tcrgite. 



Stic/ma.— This is used in two distinct senses: (i) Iu the wings of many Diptera 

 is a more or less clearly defined, darkened (generally yellowish, brown 



