226 C. H. Osten Sacken: Diptera 



Dacus ferrugineus (Wied.) Macquart, D. E. Suppl. IV, 284. 

 One of my specimens ($) agrees exactly witli Macquart's description; 

 another, also a 9, has a black spot on the scutellum, but no black 

 marks on the front femora; a third ($) is much smallei-, less thau -ja 

 of the size of the other; the median reddish thoracic stripe is wanting, 

 the apical brown spot on the wings is smaller; the design of the ab- 

 domen is.the same. A female from the Andaman Isl., in my collection, 

 agrees with this last specimen in the coloring, but is larger. 



Bactrocera maculipennis Dol. 1. Bijdr. p. 10, Tab. I, f. 1 

 Is exactly like D . ferrugineus , except that, in Doleschalls drawing, the 

 median thoracic stripe is more marked on the posterior portion of the 

 thorax than in front, and is more yellow than ferruginous. About 

 D. conformis Dol. 3 Bijdr. 50, the author says: ,,simillima maculipenni 

 Dol.", but does not state in what the difference consists. 



There are therefore, either a number of closely resembling species, 

 or this is a wide-spread and variable species. 



Ptilona brevicornis v. d. Wulp, Tijdschr. etc. XXIII, 135, 

 Tab. XI, f. 6. 7. (Sumatra). 



The color of the abdomen in my specimens is somewhat diiferent 

 from Mr. v. d. Wulp's description: the proximal portion of it is altogether 

 yellowish, embracing the first (double) segment, and the anterior margin 

 of the second ; in some specimens ( $ and Q. ) the whole second seg- 

 ment is yellowish. The length is given as 9 mm.; my largest specimen 

 is a little more than 7 mm., without the ovipositor. The agreement of 

 the wings is perfect, and the presence of the costal bristle leaves me 

 little doubt about the Identification. 



JRioxa s^). A Single female. Mr. Walker published a Rioxct 

 lanceolata in J. Pr. L. Soc I, 35, Tab, II, f. 3. (Malacca, Borneo), 

 about which later (1, c. I, 132) he observes that it is variable in the 

 distribution of the spots on the wings. My specimen looks very much 

 like the above quoted figure, except that the streak on the disc of the 

 wing, and the dot at the end of it, are wanting. Still more like my 

 specimen is the figure of Ptilona sexmaculata v. d. W. (Sumatra Exped. 51, 

 Tab. III, f. 11 (5), only the white dot at the end of the first vein is 

 wanting; the dot at the end of the sixth vein is almost imperceptible. 

 Under such circumstances, I prefer to abstain from describing the species. 



Note on the Genus Rioxa. As far as I can judge from the 

 Single specimen before me, Rioxa may be distinguished from Ptilona 

 as foUows: 1. the arista is plumose on one side only; 2. there is a 

 praesutural bristle in the humeral thoracic region, (no such bristle in 



