s Introduction. 



median organ is a prolongation of his ,Strecicsohle" at the lower 

 surface of t iie prætarsus ; he terms it „Sohlenlåppchen" (Lobus plantaris), 

 the pulvilli he terms „Seitenlåppchen" (LobuU lateraies). Yet I think 

 \ve may here very conveniently term the organ empodiiim whatever 

 may be its origin. Moreover I do not quite understand de Meijere 

 wlien he (p. 434) says: ,Die Streciiplatte, die Gleitsohle und das 

 Enipodium lassen sich meistens ohne Miihe erkennen" ; but on p. 43G 

 says: ,Indem dieser Sohlenlappen den meisteii hijheren Dipteren 

 eigentiimlich ist, daselbst aber das Empodium entvveder ganz fehlt 

 oder doch nur als kleines Rudiment vorkommt." 



The terminology of the venation of the wings is a question that has been 

 nnich confused. and, as well known, different authors use up to this day 

 dififerent terms. After the works of Adolph, Brauer and Redtenbacher 

 it now ought to be the time when a terminology with terms indicaling the 

 homolo gies for all orders should be used. It is, however, fortunate that 

 the terms used f. inst. by Schiner and Van d. Wulp for a great deal are 

 applied to veins really homologous in the different families, and only 

 in relatively few cases this is not so, what I hope to point out in the 

 particular piaces. The important observation of Adolph concerning the 

 convexity or concavity of the veins must absolutely be taken into 

 consideralion. It seems to me that the way adopled by Redtenbacher 

 (Vergleich. Stud. iiber das Fliigelgeåder der Ins., Ann. d. K. K. naturh. 

 Hofmuseums, Wien, I, ISSlV) is the correct and conforms with wliat 

 really is found in nature, and he has also compared the wings of all 

 orders. According to him tlie wings of all orders including Diptera, 

 with regard to the veins, fall in five fields with convex veins: 1. the 

 costal held with the vein I. -2. the radial field with vein III, 3. the 

 medial field with vein V, 4. the cubital field with vein VII and •">. the 

 anal field with vein IX ; tliese five systems of convex veins arc separated by 

 systems of coneave veins which he indicates by II, IV, VI, VIII and X. Be- 

 tween the branches of a convex vein coneave branches may occur, and be- 

 twcen the branches of a coneave vein convex branches may occur; tliese 

 are indicated by the arabic figures appended to the roman numerals, even 

 numbers indicating the coneave, uneven numbers indicating the convex 

 branches. As said above. the terminology used by Schiner and 

 van d. Wulp to a great degree indicates homological veins with the 

 same names, and I shall therefore, in order to avoid confusion, chiefly 

 use tliese terms. The figures (figs. 2 and 3) show the terms used here 

 together with the indications of Redtenbacher; it wiU tlien ahvays be 

 possible, also with the terminology used here, to compare the wings with 

 wings in other orders, when once a terminology uniform for all orders 

 is introduced, and lo find tiie homological veins. It is thus so 



