NO. 12 FLYING APPARATUS OF BLOW-FLY — RITTER 19 



of the thorax. This protuberance is the processus duplicatus (pi. 

 3, fig. 8; pi. 4, fig. 9, du). It is divided into two secondary pro- 

 tuberances by a shallow saddle. The proximal protuberances ride, 

 as it were, on the sella processus postalaris. Of the distal protuber- 

 ances, one, the processus analis (pi. 3, fig. 8; pi. 4, fig. 9, an), is 

 directed anally, the other rostrally. The former corresponds to the 

 notch in the processus pteralis alse 4; the latter, the processus ros- 

 tralis (same figs., ro), clasps the pterale B (pi. 8, fig. 24; pi. 9, 

 fig. 25, ptB) and extends as far as the processus pteralis alse 2. 



2. Pterale B (pi. 3, fig. 7; pi. 8, fig. 24; pi. 9. figs. 25, 26; ptB). 

 This pterale is the unguiculus of Lowne. It is situated vertically 

 and connects the upper and under sides of the joint. From the 

 upper side a strong protuberance, the processus proximalis (pi. 3, 

 fig. 7, x) arises. This protrudes beyond the processus rostralis of 

 pterale A. From the lower side two important protuberances, 

 the processus dentales (pi. 3, fig. 7, de), arise. In the space between 

 these two protuberances lies the anal convexity of the processus 

 pteralis thoracis V. Besides those mentioned above there are three 

 smaller protuberances which appear to be of minor importance. 



3. Pterale C (pi. 9, fig. 26, ptC ; pi. 10, figs. 27, 28, ptC). This 

 pterale is the hypopterigium of Lowne. It consists of a skeletal 

 piece surrounded by a hyaline elastic mass. The skeletal portion has 

 somewhat the form of a pistil with a strongly expanded head and 

 a conical stem. Pterale C is in contact with the stay V. The head 

 of the pterale lies in the deep, strongly chitinized, articular fossa of 

 the processus pteralis alse 3 (see pi, 9, fig. 26). 



C. THE ALAR PORTION (PROCESSUS PTERALES AL^) 



The marginal vein and the remigium form the principal part of 

 the alar portion of the joint. The remaining proximal parts of the 

 wing take hardly any part in its formation. 



Four processus pterales alse are to be distinguished : 

 I. Processus pteralis alec i (pi. 8, figs. 23, 24; pi. 9, figs. 25, 26; 

 pti). This process appears as a continuation of the club-shaped basal 

 protuberance of the marginal vein. It resembles a hand held hollow, 

 articulates with the processus pterales alse 2 and 3, and is separated 

 from the marginal vein by a sharp incision and a clear, feebly chit- 

 inized zone. Rostrally, it is covered by a scale-like, hairy piece, the 

 tegula (pi. 8, figs. 23, 24; pi. 9, figs. 25, 26, t) , which extends 

 over the whole joint. The names pre-epaulet, epaulet and sub- 

 epaulet, with which Strauss-Diirkheim designated different portions 



