No. 64] DIPTERA OF CONNECTICUT: MORPHOLOGY 57 



bears the paired internal apophyses, or furca, for muscle attachment 

 (see Fig. 8, Plate 3 of paper by Crampton, 1925b) . The metasterum, 

 hs of Fig. 6, A, B and O, is quite distinct in most Diptera, but the 

 meropleural sclerite, 7npl of Fig. 6, C, is usually interpreted as the 

 "metasternum" in tiie higher Diptera, and the mesothoracic meron, me 

 of Fig. 6, A and D, is usually interpreted as the "metasternum"' in the 

 lower Diptera, although these sclerites are sometimes regarded as the 

 posterior region of the mesosternum or even as the episternum of the 

 metathorax (Young. 1921, in the culicids, etc.). Young (1921) con- 

 siders that the sclerite labelled hs in Fig. 6, B, C, E, etc., represents 

 the pleurotrochantin, instead of the sternum of the metathorax, but 

 the ventral portion of this sclerite, at least, belongs to the basisternal 

 region of the metasternum. 



6. Basal structures of the wings 



The venation of the wings has been figured in a separate chapter 

 by Dr. Friend, so that only the basal structures of the wings will be 

 discussed here. These include the axillary sclerites, calypteres, axil- 

 lary lobe, and other structures not actually parts of the veins them- 

 selves. 



The AxiUa?'y Sclerites. The axillary sclerites, alar ossicles or 

 pteralia, are the small plates situated between the lateral margins of 

 the notum and the bases of the wing-veins. They are apparently 

 formed, in part, as detached portions of the lateral region of the no- 

 tum, and partly as detached basal portions of the wing-veins, or as 

 sclerotizecl areas at the bases of the veins. These articulatory sclerites 

 enable the wing to be laid back and stretched out more readily, and 

 some of them are involved in the movements of flight. The sclerites 

 of one of the Tabanidae (Fig. 7,1), wliich occupy a position inter- 

 mediate between the lower and the more specialized Diptera, will serve 

 to illustrate the structures in the basal region of the wing of a typical 

 dipteran. 



The tegula or "epaulet", tg of Fig. 7, 1, and Fig. 6, A, C, and E, 

 is a small anterior sclerite situated in an incision of the lateral region 

 of the notum just in front of the anterior wing process of the notum. 

 This sclerite is liomologous with the sclerite called the tegida in the 

 Hymenoptera and other insects, and Sharp (1897) very justly ob- 

 jected to the application of the term tegula to other structures (calyp- 

 teres) in the Diptera. 



The sclerite, hac of Fig. 7, 1, was originally called the parategula 

 in the Diptera, but Shannon (1924) has suggested that it be called the 

 basicosta, and this designation is a very appropriate one for this 

 sclerite. since the sclerite in question apparently represents a de- 

 tached basal portion of the costal vein of the wing. Snodgrass (1935) 

 more recently refers to this sclerite as the humeral plate. 



The sclerite, no of Fig. 7, 1, is called the first axillary or the no- 

 topterale (notale). and probably represents a detached portion of the 

 lateral edge of the notum. It articulates with the lateral edge of the 

 notum, and its anterior neck-like region abuts against the base of the 

 subcostal vein. 



