J 02 CONNECTICUT GEOL. AND NAT. HIST. SURAEY [Bull. 



is actually the sixth sternite throughout the series here figured, seems 

 inevitable; and instances such as this, demonstrate the superiority of 

 the method of comparative morphology for solving such problems, 

 although this method is little esteemed by recent investigators ! 



The sinistral spiracle of the seventh segment is borne close to the 

 anterior border of tlie synsternite 7s + 8s in the male housefly (Fig. 

 13, F), indicating that the seventh sternite, with which the spiracle is 

 usually associated, plays but a small part in the formation of the 

 synsternite. The surstyli, ss, like the cerci, ce, are broad and flat; 

 and in the housefly they become approximated ventrally to form a 

 divided plate-like structure which was mistaken for the divided ster- 

 nite of the genital segment by Berlese (1909) and Hewitt (1914), but 

 a comparison of the parts with those of the other insects in the series 

 here described, readily reveals the true nature of these structures. 



The sclerites in the metopiid (sarcophagid) fly Sai^cophaga facu- 

 lata shown in Fig. 14, B, resemble those of the calliphorid Phormia 

 regina shown in Fig. 13, E, but the sixth tergite has been almost ob- 

 literated in Sarco'pfiaga (Fig. 14, B), and the synsternite 7s + 8s is 

 greatly elongated. The sinistral spiracle of the seventh segment is 

 situated near the middle of the synsternite, which may indicate that 

 a relatively large portion of the synsternite is formed by the seA^enth 

 sternite. 



In the cordylurid Parallelonima shown in Fig. 14, G, the syn- 

 sternite 7s + 8s is greatly developed, and the sinistral spiracle of the 

 seventh segment is situated far back in the synsternite. The sixth 

 tergite U is very large in PaTalleloimmi^ unlike the insects described 

 above, in which the sixth tergite tends to become reduced or atrophied. 

 The copulatory lobes of the fifth sternite fgl are greatly developed in 

 ParaUeloimmi^ and the surstyli ss are also greatly developed in this 

 insect. 



The sclerites of other male Cyclorrhapha may be readily com- 

 pared with some of the various types here described, particularly 

 with the common fly Phormia regina (Fig. 13, E, Fig. 9a, A, etc.), 

 which is a rather typical cyclorrhaphan, intermediate between the 

 lower and the more highly specialized forms, and therefore well suit- 

 ed to serve as the basis for comparison with the higher and lower 

 representatives of the group. The interpretations and terminology 

 suggested by other investigators may also be taken up at this point, 

 indicating those which seem to be the most acceptable, and giving the 

 reasons for discarding those which are less so. 



Berlese (1909) considers that the parts revoh^e in a counter- 

 clockwise direction (instead of in a clockwise direction) in ih^ post- 

 abdomen of the Syrphidae, and consequently interprets the displaced 

 sternites as ^'tergites*' in his figures of Eridalis, etc. Metcalf (1921), 

 on the other hand, rightly concludes that the parts revolve in a clock- 

 wise direction in the Syrphidae, and correctlv identifies the displaced 

 sternites, Avith the exception o fthe inverted eighth sternite, which he 

 designates as an "urite" or complete segment. Unfortunately, how- 

 ever, Metcalf accepts Berlese*s suggestion that the basal segments 



