G4 CONNECTICUT OEOL. AND NAT. HIST. SURVEY [BulL 



meron, em, but the meral region of the coxa becomes membranous so' 

 that the mobility of the leg is not impaired. The meral region of the 

 jnesothoracic coxa is frequently mistaken for the posterior portion of 

 the mesosternum. or for the metasternum, or even for the metathoracic 

 epi sternum, etc. The metathoracic coxa is not divided into a eucoxa 

 and meron in tlie Diptera, nor is the prothoracic coxa so divided in 

 any insect.s. although a narrow marginal region (basicoxa) in the basal 

 regi(m of the prothoracic coxa includes a posterior area, which is ho- 

 mologous with the meron of the mesothoracic coxa. This area is small 

 and unimportant in the prothoracic coxa; but it becomes greatly en- 

 larged and occupies the greater portion of the posterior region of the 

 coxa in the mesothoracic leg. 



The trochanter, tr, has a movable articulation with the coxa, but 

 is immovably united with the femur in most insects, and usually ap- 

 pears to be merely a demarked basal region of the femur, although 

 Snodgrass (1927) and others consider that the trochanteral region of 

 certain insects represents the union of two segments of the leg of such 

 arthropods as the Crustacea, etc. The trochanter is usually small and 

 relati^'ely unimportant in the Diptera. 



The fennir, /e, and the tibia, ti, are usually the longest segments 

 of the leg, and are extremely elongated in the Tipulidae. In some 

 Empidae (Fig. 8, G) and Ephydridae (Fig. 8, M) the prothoracic 

 femur, fe^ is rather stout and bears strong bristles; and the tibia tits 

 against the femur in a fashion very suggestive of the fore legs of the 

 mantids and other predaceous insects. In the male Sepedon shown in 

 Fig. 8, A, the metathoracic femur and tibia are bent in a peculiar 

 fashion, and the femur is provided with stout processes wliich may be 

 used in mating. The mesotlioracic femur is similarly provided with 

 -tout s]^ine-like processes in the stratioinyid shown in Fig. 7, C. In 

 the male syrphid shown in Fig. 8, F, the prothoracic femur bears long 

 hairs bordering a'^roove the purpose of which is not known. In the 

 empid shown in Fig. 8. D, the femur and tibia of the posterior legs 

 are bordered by broad, flattened, scale-like setae which give a feathery 

 appearance to the legs; and structures somewhat similar to these are 

 borne on the hind tibiae of the tachinid Trichopoda pennipes. al- 

 though there is no close relationship between these two insects. 



One or more distinct short spurs, called tibial spurs, are borne at 

 the distal end of the tibiae, and the number of these tibial spurs is a 

 feature used in classification. According to Comstock (1924, p. 778), 

 "The number of tibial spurs borne by the different pairs of legs is 

 often^ indicated by a brief formula, as, for example : 'tibial spurs 

 1:2:2* indicates that the lore tibiae bear each one spur; the middle 

 tibiae, two; and the hind tibiae two." 



The tarsi, ta, are typically pentamerous in the Diptera; and the 

 hye segments which compose the tarsus may be called the tarsomeres. 

 ihe basal tarsomere, ht, (Fig. 8) is the basitarsus, and the distal tar- 

 somere, <i25, is the distitarsus. The basitarsus is usually called the 

 "metatarsus", but the designation meta-tarsus signifies the entire tar- 

 sus of the metathoracic leg, and should not be applied to any other 

 structures. 



