i 4 R. W. CROSSKEY 



Palpostomatini or in both sexes of many Phasiini). The frons is of equal width 

 in both sexes in all Siphonini and many Phasiinae, but rarely in other groups. 



frontal setae. The setae of the paired rows of setae standing on the inner edges 

 of the parafrontals (Stirnborsten of Mesnil) (Text-fig. 3). 



These setae are strongly or moderately developed in most Tachinidae but 

 may be weak and hair-like in Rutiliini and Phasiini and occasionally in other 

 groups. The rows may be partially obliterated in forms with holoptic or 

 semi-holoptic heads. Normally the setae of each row are directed inwards so 

 they cross medially (cruciate frontals), but in a few forms some or all of the 

 frontal setae are directed upwards and backwards (reclinate frontals). In 

 Phasiinae and Proseninae the rows of frontal setae extend downwards only to 

 the level of the antennal base or but slightly beyond, but in most Tachininae 

 and Goniinae the rows reach downwards at least to the level of the middle of 

 the second antennal segment and often beyond (in the latter case the rows 

 extend well down on the parafacials where, particularly in males, they may be 

 irregularly doubled, e.g. in Voriella). 



gena. The lateroventral part of the head between the bottom of the eye and 

 the peristome or oral cavity {cheek, jowl, peristom of Mesnil) (Text-fig. 1). 



The depth of the gena from the lowest point of the eye to the ventral margin 

 of the head when seen in profile can provide an important character, especially 

 its proportion in relation to eye height or width of the profrons (e.g. much narrower 

 in Carceliini than in other tribes of Goniinae). 



genal dilation. The swollen haired part of the gena continuous with the postbuccae 

 and occiput (Occipitale Erweiterung auf dem Peristom of Mesnil) (Text-fig. 2) . 



Commonly the genal dilation occupies most of the gena and reaches well 

 forwards towards the vibrissal angles, but in some forms is reduced or virtually 

 absent (in which case the gena is bare or mainly so). The genal dilation is 

 normally extensively haired and sometimes bears a few stronger setae. 



hair fascicles. Dense, often convergent, tufts of hair on the abdominal venter. 

 These are a secondary sexual character of males and occur mainly in a few 

 genera of Goniinae. When present they are normally restricted to the venter 

 or sides and venter of the fourth tergite (e.g. Palexorista) or of the fifth tergite 

 (e.g. Paropsivora, Zoster omeigenia) , but occasionally are present on two successive 

 tergites. 



humeral calli. The paired convexities forming the anterolateral corners of the 

 thoracic dorsum (humeri, posterior pronota, shoulders) (Text-fig. 4). 



humeral setae. The setae standing on the humeral calli (Text-fig. 4) . 



The number and arrangement of these setae, particularly whether the main 

 ones stand in a straight line across the callus or in a triangle, is taxonomically 

 important at several levels. Usually each callus bears at least two differentiated 

 humeral setae, but there may be only one or even no clearly differentiated seta 

 (e.g. in Phasiini). 



infrasquamal hairs. A group of minute hairs or setulae on the mediotergite 

 adjacent to the base of the lower calypter (Text-fig. 7). 



Presence or absence of these hairs is sometimes a useful minor taxonomic 



