Sept., I9I3-] Melander: Synopsis of Diptera. 223 



inclination must be observed. This is particularly true of the bristles 

 on the front. The presence or absence of the anterior dorsocentrals, 

 of the presutural, of the sternopleural, mesopleural, and rarely of the 

 pteropleural, the number and direction of the scutellars, require notice. 

 The postverticals, oral vibrissa, preapical tibial bristles, acrostichal 

 and mesopleural setulae, prothoracic bristles and the hairs of the second 

 antennal joint are taxonomically important. The ocellars, vertical 

 bristles, occipital, supra-alar, coxal, femoral and abdominal bristles 

 are less utilized. However, any of the bristles may vary, and abso- 

 lute stress should not be laid on the presence or absence, size or incli- 

 nation of certain of the hairs. Within reasonable limits the chastotaxy 

 is reliable and offers a most valuable guide to the genera and species. 



Within the group the proboscis is quite variable. It is tw^ice 

 broken, the basal and end sections directed backvvard, the middle sec- 

 tion forward. Sometimes it is short and largely fleshy {Meoneura, 

 Chiramyia), again it is elongate, slender, strongly chitinized and 

 resembles a piercing organ (Milichiina). Even where it is of medium 

 size the labella may be broad and fleshy (Rhicnoessa) or may be 

 needle-like (Desmometopa). The palpi range from largb and porrect 

 to small. Their shape and hairiness should be noted. The develop- 

 ment of the clypeus (variously called the prelabrum, upper-lip, ful- 

 crum, pharynx, Schlundgerust, Chitinhufeisen) is important. Hendel 

 restricts the term clypeus to the center of the face (antennal foveae, 

 Gesichtsleiste), a structure which still lacks a convenient English 

 name. The center of the face is bounded by the facialise or facial 

 ridges, which are more or less evidently separated from it and from 

 the gense. Sometimes the front is complex, with paraorbits, inter- 

 frontalia, ocellar triangle, cruciate bristles, and specialized stripes 

 (Chitinleisten) between the paraorbits and the ocellar triangle, all of 

 which may be present {Desmometopa), marking the front with a 

 letter M. Sometimes the front is simple, pollinose or not, but with 

 the ocellar protuberance alone differentiated. The shape of the lunule 

 is also noteworthy. 



The shape and hairiness of the third antennal joint and less so of 

 the second; the development of the arista, whether slender, elongate, 

 pubescent, or with small or large basal segment ; the excavation or 

 convexity of the upper occiput, and the profile of the head should be 

 noted. Less important is the structure of the thorax, abdomen and 



