ZooL.— Vol. II.] WHEELER— DOLICHOPODID^. II 



Pelastoneurus Loeiv. 



The species of this genus, which is peculiar to America, 

 do not exhibit very prominent plastic characters. Almost 

 the only satisfactory morphological features are to be 

 found in the structure of the hypopygium. On these 

 it seemed possible, at first, to separate the species into 

 two genera, assigning to the one those forms which have 

 long and slender lamellae, and to the other those with short 

 lamellae and swollen hypopygial scape, but I abandoned 

 this attempt on failing to find other correlated characters in 

 my specimens. Aldrich has founded a new allied genus, 

 Meta-pelastoneurus, on a peculiar form of hypopygium. 

 Possibly Loew's Pelastoneurus furcifer is also to be as- 

 signed to this genus. The genus Pelastoneurus promises to 

 be a large one when all our species are known. Descrip- 

 tions of six new species and a dichotomic table of all the 

 known North American forms are given below. 



1 . Postocular cilia pale 2 



Postocular cilia black 9 



2. Fore coxae entirely yellow 3 



Fore coxae more or less infuscated 4 



3. Arista short, tapering rapidly cognatus Loew. 



Arista long, scarcely tapering neglectus, sp. nov. 



4. Thorax with alternate green and cupreous bands. 



alternans Loew. 

 Thorax with at most one median cupreous band 5 



5. Hypopygial lamellae long and narrow 6 



Hypopygial lamellae short lineatus Ald. 



6. Lamellae linear, straight, with rounded tips vagans Loew. 



Lamellae not linear, nor straight 7 



7. Tips only of the fore coxae yellow occidentalism sp. nov. 



Bases only of the fore coxae infuscated 8 



8. Hind tibiae strongly infuscated argentiferus Ald. 



Hind tibiae yellow .floridanus, sp. nov. 



9. Wings banded with black pictipennis, sp. nov. 



Wings not banded 10 



10. Wings distinctly blackened lugubris Loew. 



Wings grayish hyaline 11 



11. Posterior edge of thorax with a glittering white spot. 



longicauda Loew. 

 No such spot on the thorax 12 



12. tlypopygial lamellae furcate furcifer Loew. 



Hypopygial lamellae not furcate 13 



