86 



PROF. M. BEZZI. 



species ha\e this character wanting or very Httle developed. The Oriental species 

 with no praescutellar bristles (Monacrostichus and related forms) have also the 

 hind border of the wings not indented at the end of the anal vein. It seems therefore 

 that there is some correlation between the presence of the praescutellar bristles and 

 the presence of the supernumerary lobe in the male. 



The attempt to divide the Ethiopian species into the two genera Dacus (s. str.) 

 and Leptoxyda, seems to be at present not satisfactory, although accepted by 

 Hend 1 in his recent synopsis of the genera of the Trypaneids {Wien entom. 

 Zeitung, xxxiii, 1914, p. 74). It is indeed very difl&cult to find a dividing 

 line between the species with free and those with fixed abdominal segments, 

 and between the species with a flattened ovipositor and those in which it is 

 cyhndrical. Therefore I have not adopted this division in the present paper. 

 On the other hand, I have found a better character for dividing the Ethiopian 

 species in the thoracic chaetotaxy. Some species, which are usually of larger size, 

 have three supra-alar bristles, the anterior one being developed like the others ; 

 I propose to call this group Tridacus, subgen. n. The remaining species, which are 

 smaller, have no anterior supra-alar bristle ; and as they contain D. oleae, I will 

 reserve for these the name Dacus {s. str.). With this later group the genus Leptoxyda 

 must be considered synonymous, unless it be regarded as distinct, with the single 

 typical species longistylus. 



p.sa 



Fig. 2. Dorsal view of the thorax of a Dacus, to 

 show the chaetotaxy : — scp, scapular bristles ; npl, 

 notopleural bristles ; mpl, mesopleural ; a.sa, 

 anterior supra-alar ; p.sa, posterior supra-alar ; 

 a, apical bristles. 



The Ethiopian species of Dacus (s.l.) are not yet well known, but rather numerous 

 forms have been described ; there are also three tables of determination (without 

 including the very incomplete one by Dr. Sack, 1908), two given by me in 1908 and 

 1909, and one by Dr. Speiser in 1910. 



