68 DIPTERA OF NORTH AMERICA. [PART III. 



like one of the more corpulent American species of Baccha ; fcr 

 instance, Baccha capitata Lw. The second longitudinal vein, 

 which in Euolena forms a short stump inside of the submarginal 

 cell, bears, in this genus, almost at the same place, similar 

 stumps, not only in the submarginal, but also in the marginal 

 cell. The most striking difference, however, lies in the structure 

 of the feet, as Euolena has the four posterior femora remarkably 

 long and slender, which is not in the least the case with Idiotypa. 



The genus STENERETMA, which will be characterized in the 

 third part, treating of the North American species, is related to 

 Idiotypa. 



The South American species described by Fabricius once as 

 Scatophaga trimaculata and another time as Dacus Jlav us, and 

 which Wiedemann placed in the genus Trypeta, does not belong 

 in this genus at all, but in the present group of the Ortalidse. 

 The description, which Macquart gave of his CCELOMETOPIA 

 ferruginea, contains so much which is entirely applicable to 

 Fabricius's species, that I have no doubt that the latter species 

 was the very same from which the description of Coelometopia 

 ferruginea was drawn. When Macquart says that in C. ferru- 

 ginea the middle femora alone are armed, this statement is pro- 

 bably based upon an insufficient observation ; when he calls the 

 last three tarsal joints white, this seems to be a lapsus calami, 

 as the figure shows nothing of the kind, and as on two of the 

 tarsi the first joints are even represented as much paler than the 

 following ones ; the latter probably being Infuscated, as they are 

 in Fabricius's species. Should even, contrary to my supposition, 

 Macquart's species be different from that of Fabricius, they will 

 at all events belong to the same genus. 



The Odontomera maculipennis of Macquart from Colombia, 

 South America, seems very closely allied to Coelometopia; 

 Macquart's own statements show that it agrees in so many 

 characters with Coelometopia trimaculata, that it may be trans- 

 ferred to the same genus with it; one would even be led to sup- 

 pose that it is nothing but the female of Codomelopia trimaculata. 

 "With the above mentioned Odontomera ferruginea Macq. (not 

 Coslometopia ferruginea Macq.) Odontomera maculipennis has 

 too little in common to be considered as belonging to the same 

 genus. 



A pretty species from Cuba, which will be described in the 



