Vol. XXVJi] ENTOMOLOGICAL NEWS. 259 



Mycetobia and the Classification of the Diptera. 



By FREDERICK KNAB, Bureau of Entomology, U. S. Dept. of 



Agriculture. 



In a paper read at the ninth annual meeting of the Entomo- 

 logical Society of America, the writer proposed a new group- 

 ing of the lower families of Diptera, generally called Nema- 

 tocera, dividing them into two series according to the char- 

 acter of the larval respiratory system. 1 In one series, Oli- 

 goneura, were placed those forms in which the larvae showed 

 the more primitive condition of a series of lateral spiracles, 

 such as occurs in most terrestrial insects. In the other series, 

 Polyneura, were grouped those forms in which the larval res- 

 piratory system had become profoundly modified in adaptation 

 to aquatic life, a single pair of large functional spiracles oc- 

 curring posteriorly. The grouping thus brought about appeared 

 more natural also when the adult characters were considered. 



In examining the available data concerning the larval spir- 

 acles, but one seeming contradiction was found. This was the 

 genus Mycetobia, universally considered a member of the 

 family Mycetophilidse. Its larva was said to differ from all 

 the others of that family by possessing but a single pair of 

 spiracles, posteriorly situated, and showing a remarkable re- 

 semblance to the Rhyphidge. This contradiction within a large 

 and otherwise homogeneous group was already strongly felt by 

 Osten Sacken. 2 He accepted the statements of three most 

 careful workers, Lyonet, Dufour and Ferris all agreeing 

 on this point, but ended the discussion of the subject with the 

 remark, "this is a problem yet to solve." The writer, finding 

 Mycetobia the only case conflicting with his proposed group- 

 ing, became convinced that some error existed and suggested 

 that the three great observers just mentioned might after all 

 have been mistaken. It has now been made clear that they 

 were correct, but the seeming contradiction has been ex- 

 plained in an unexpected manner, most gratifying from the 

 view-point of the writer's ideas. 



1 The Nemocera not a natural group of Diptera. Ann. Ent. Soc. 

 Amer.. vol. 8, 1915, pp. 93-98. 



2 Berlin. Entom. Zeitschr., vol. 37, 1892, pp. 442-443. 



