No. 64] DIPTERA OF CONNECTICUT: MORPHOLOGY 83 



female rhasfionid (leptid) shown in Fig. 9. F. the segments of the 

 postabdomen have become slender and are widely spaced, with mem- 

 branous intersegmental regions, is, between them, to permit a tele- 

 scoping of the segments which is very suggestive of the condition 

 exhibited in females of the muscoid Cyclorrhapha. 



The hypogynium. or sternite of the eighth segment, 85, projects 

 posteriorly beneath the ninth segment in the rhagionid (leptid) 

 shown in Fig. 9, F, in a manner rather characteristic of the lower 

 Brachycera, but not so prominently as in the stratiomyid shown in 

 Fig. 9, B. The ninth and apparent tenth segments are still distinct 

 in the rhagionid (leptid) shown in Fig. 9, F (and to some extent in 

 the stratiomyid shown in Fig. 9, B) ; but the apparent tenth segment 

 is probably a composite "segment" composed of the true tenth seg- 

 ment and the cerci-bearing eleventh segment (with the telson) which 

 unite to form the proctiger, pgr, or "anal segment". The dorsal 

 plate, epr. of the proctiger of the stratiomyid shown in Fig. 9, B and 

 G, is called the supra-anal plate (epiproct) and its ventral plate, hpr, 

 is called the subanal plate, or hypoproct. (Compare also the so-called 

 postgenital plate described by Gerry, 1932.) 



The cerci are two-segmented in the rhagionid shown in Fig. 9, F, 

 and are composed of a broad basal segment or basicercus, dc, and a 

 smaller distal segment, or disticercus, which bears what appears to be 

 a sense organ near its caudal margin. The two-segmented cerci, ce, 

 of the stratiomyid shown in Fig. 9, B and G, are slender and cylindri- 

 cal, and resemble the cerci of certain Mecoptera in many respects. 



In the female asilid shown in Fig. 10, G, the eighth sternite, 85, 

 projects posteriorly beneath the ninth segment in a manner rather 

 typical of certain lower Brachycera. The ninth tergite is divided 

 into hemitergites, bearing stout spine-like structures. Hardy, 1935 

 (Annals and Magazine of Nat. History for 1935, Ser. 10, Vol. xvi, p. 

 425) figures similar spine-bearing plates called acanthophorites in the 

 dolichopodid Scla-pus and compares them with the acanthophorites of 

 the Asiloidea with reduced and modified spines which he further com- 

 pares with "the spines on the (apparent) lamellae of the Proctacan- 

 ^/ms-group within the Asilinae." Spine -bearing structures occur in 

 the terminal abdominal region of the peculiar fly Lampromyia {\\9=,- 

 ually classed with the "Leptidae") and may indicate that this fly is an 

 asilid — as is also true of the thoracic sclerites and other features 

 which ally Lampromyia much more closely with the asilids of the 

 Leptopteromyia and Leptogaster types (in which the wings are very 

 like those of Larnipfomyia) than with the "leptids". Certain therev- 

 ids also have spine-bearing structures in the posterior abdominal 

 region, and the occurrence of these structures in female therevids, 

 asilids, dolichopodids, etc., is apparently of considerable phylogenetic 

 importance in pointing to a therevid-like ancestry for these forms 

 (rather than a rhagionid ancestry, from which the stratiomyids, tab- 

 anids, pantophthalmids, etc., arose), althougli the lines of descent of 

 the therevids and rhagionids merge at the base of the common stem 

 of the Brachycera in general. 



