No. 64] DIPTERA OF CONNECTICUT: MORPHOLOGY 99 



Paragiis hicolor^ shown in Fig. 13. A, stands almost at the apex 

 of the intra-syrphid series, and its modifications foreshadow many of 

 those occurring in the muscoid series, ahhough Paragus exhibits too 

 many specializations of its own to serve as the starting point for the 

 development of the muscoid series. Paragus (Fig. 13, A), however, 

 does illustrate very nicely how the lateroverted seventh sternite 75 

 (below which lies the displaced dextral spiracle) unites with the 

 inverted eight sternite 8s (from which it is separated by an incom- 

 plete suture) to form a synsternite, as in the higher Cyclorrhapha 

 shown in Fig. 13, C and D; and the sixth sternite 6s of Paragus (Fig. 

 13, A) is asymmetrically developed, and lies in front of the later- 

 overted seventh sternite 7s, much as it does in Fig. 13, B and C, etc. ; 

 and the fifth sternite 5s of Paragus (Fig. 13, A) is widely emarginat'e 

 posteriorly, suggesting the origin of the posterior incision in the 

 fifth sternite of the insects shown in Fig. 13, D and E, which results 

 in the formation of the copulatory lobes pgl of the fifth sternite of 

 these insects. 



In the stratiomyid Ptecticus, shown in Fig. 12, C, the distal seg- 

 ments of the genital forceps, st, are broad and flat, and the basal seg- 

 ments, coii, tend to unite with the ninth sternite, 9s, strongly sug- 

 gesting the condition exhibited by the structures labelled st and cxi 

 in the syrphid shown in Fig. 14, H, in which these structures are 

 provisionally interpreted as the modified segments of the genital 

 forceps. 



It was formerly suggested by the writer (Crampton, 1936 and 

 1941) that the gonapophyses ago and pgo of such higher Diptera as 

 those shown in Fig. 13,1), E, etc., might represent the highly modi- 

 fied segments of the genital forceps, cxi and st^ of such lower forms as 

 those shown in Fig. 12, C, or Fig. 14, H, etc. What appear to be dis- 

 tinct gonapophj^ses, however, occur in the stratiomyid Ptecticus, 

 shown in Fig. 12, C, (where the gonapophyses, labelled 'pgo^ are dot- 

 ted to indicate that they lie within the genital forceps) as well as in 

 certain Therevidae and other forms in which distinct genital forceps 

 (labelled cxi and st in Fig. 12, C) likewise occur, so that the gona- 

 po]3hyses of the higher Cyclorrhapha can hardly represent the 

 modified segments of the genital forceps of the lower Diptera. It 

 is therefore preferable to refer to the gonapophyses of the higher 

 Diptera simply as the anterior and posterior gonapophyses, although 

 the term "gonapophyses" is rather misleading for these sti-uctures of 

 male Diptera, since the designation gonapophyses is usually applied 

 to the parts of the ovipositor, etc., of female insects (in which the 

 parts have no relation to the structures of male Diptera), and the 

 briefer designations pregonites and postgonites are therefore suggest- 

 ed for the structures labelled ago and pgo in the higher Diptera shown 

 in Fig. 13, D, E, etc. 



In the insects shown in Fig. 14, A and C, and in Fig. 10, B and I, 

 the entire sixth segment is little affected by the torsion process, but the 

 seventh sternite 7s of Fig. 14, C, and Fig. 10, B, becomes strongly later- 

 overted. and adheres to the inverted eighth sternite 8s (compare also 



