No. 64] DIPTERA OF CONNECTICUT: MORPHOLOGY 113 



(1928) J Pattoii (1932), and other recent dipterists agree in interpret- 

 in,o: these structures as the cerci in the males of the higher Diptera, 

 but Snodgrass (1935) refers to them as "the lateral lobes of the mem- 

 branous tenth segment"' in his figures of a nuile of Pollenia nulls 

 (Fig. 14, F), and apparently thinks that they have no relationship to 

 the structures which he calls the cerci in female Mecoptera. 



It is unfortunate that many recent dipterists have adopted Awati's 

 method of referring to the cerci as "anal cerci" in the higher Diptera, 

 which is either superfluous or misleading. ^There are no anterior 

 cerci to be confused with the "anal" ones, if the qualifying adjective 

 "anal" signifies structures whieli are posterior in position, as contrast- 

 ed with those which are anterior in position, so that in this case the 

 adjective "anal" is superfluous. On the other hand, if the adjective 

 "anal" implies that the cerci belong to an "anal segment", this is very 

 misleading, since the true cerci are appendages of the eleventh seg- 

 ment, whereas the anus belongs to the nou-segmental telson situated 

 behind the cercus-bearing eleventli segment in embryo insects, etc.. 

 and the cerci therefore do not belong to an "anal segment" and should 

 not be referred to as "anal cerci" in this connection. 



The cerci, ce, and surstyli. ss, of Fig. 13, I) and E, etc., of 

 the males of the higher Diptera usualh'' lie close together and pro- 

 ject ventro-cephalad beneath the delicate genital structures to pro- 

 tect them, while the processes of the fifth sternite, j^gl, frequently 

 extend backward below them, up to the bases of the surstyli, ss, leav- 

 ing the sensitive areas of the cerci, and the anal opening, exposed. 

 The cerci of these Diptera bear sensory setae, and INIetcalf (1921) 

 considers that the cerci are the only sensoi-y structures in this region 

 of the abdomen. 



In the male housefly shown in Fig. 10, L, and Fig. 13, F, the cerci, 

 ce, are broad flattened plates which become approximated mesally, 

 and were mistaken for the divided sternite of the genital segment by 

 Berlese (1909), who considered it to be the tenth segment, and by 

 Hewitt (1914), who considered it to be the eighth segment. In the 

 warble fly, Hi/poderma, however, Hewitt considers that the cerci rep- 

 resent the divided tergite of the tenth segment, and Edwards (1920) 

 would apparently support this view, since he states that in male Myce- 

 tophilidae, Bibionidae, etc., the tenth tergite is divided into two "hairy 

 lamellae resembling the cerci of the female." Edwards also describes 

 a supposed sternite of the tenth segment in males of these insects, 

 but it is rather doubtful that a true tenth sternite is present in male 

 Diptera, and it may be that the paraprocts or parapodial plates, rep- 

 resenting the divided eleventh sternite (according to the embryolo- 

 gists), may persist in some of these insects to form the divided ventral 

 plate found in the proctiger of certain Diptera, but this has not been 

 definitely proven to be the case. At any rate, the cerci do not repre- 

 sent the divided tergite of the tenth, or any other segment, since true 

 cerci are the modified limbs of the eleventh segment; and if the 

 structures called cerci in male Cyclorrhapha are true cerci, they rep- 



