2o R. W. CROSSKEY 



In most Tachinidae the hind coxae are rather close to the abdominal base 

 and the posteroventral declivity of the thorax consists of a median membranous 

 area flanked by curved sclerotized areas (the metapleura). In a few forms 

 (e.g. Cylindromyia, Doleschalla) the abdomen and the metacoxae are much 

 more remote from each other than is usual and the entire posteroventral 

 declivity of the thorax forms a fully sclerotized bridge between them; this forms 

 an important taxonomic and key character. 



posthumeral setae. One or more setae standing anterolaterally on the prescutum 

 immediately behind the humeral callus (Text-fig. 4) . 



Development of these setae is rather variable and their taxonomic usefulness 

 very limited. The ph setae are usually most strongly developed in Goniinae, 

 in which two moderately strong posthumerals are normally present on each 

 side, and least strongly represented in Phasiinae and Proseninae in which they 

 may be absent or hair-like. 



postocular row. The regular row of setulae or long hairs on the upper and outer 

 edges of the occiput immediately behind the eyes (Text-fig. 3) . 



postorbits. The narrow laterodorsal strips of the head lying between the eyes 

 and the postocular rows (Text-fig. 1). 



postscutellum. The transverse swollen lobe below the scutellum and dorsal to 

 the mediotergite (subscutellum, infrascutellum, postnotum) (Text -fig. 7) . 



This is almost universally present in Tachinidae and strongly convex. It 

 is very weakly developed in a few forms (e.g. Palpostomatini) and is strongly 

 produced backwards, squared and flattened in some Phasiini (e.g. Campbellia, 

 Alophora subg. Mormonomyia). The postscutellum is always bare. 



postsutural. Behind the transverse suture of the mesonotum. 



pre-alar seta. A seta standing at the extreme anterolateral corner of the scutum 

 anterior to, and approximately in line with, the supra-alar setae (first supra-alar 

 seta of authors) (Text-fig. 4). 



This seta is of the very greatest importance in tachinid taxonomy because 

 of its variability in size, and, to a lesser extent, because of its presence or absence. 

 The seta is universally present in the Goniinae (though it may be very weak) 

 and may be either small (shorter than the first post ia seta or at most subequal 

 to it) or very large (longer and stronger than the first post ia seta and usually 

 also longer than the first post dc seta), and this distinction holds true almost 

 without exception for the differentiation of two groups of Goniine tribes. In 

 Phasiinae, Proseninae and most Tachininae the pre-alar seta is of the small 

 type, and is sometimes absent (e.g. in Phasiini, some Minthoini and sometimes 

 haphazardly in Proseninae) . 



preapical (discal) scutellar setae. A pair or more of recumbent or semi- 

 recumbent setae standing on the scutellum in advance of the marginal setae 

 (Text-fig. 5). 



prescutum. That part of the mesonotum lying anterior to the transverse suture 

 (Text-figs 4 & 7) . 

 Morphologically this is the anterior part of a divided scutum but the term 



