THE CANADIAN ENTOMOLOGIST 253 



The disposition of the types is as follows: Two in the collection of Mr. F. 

 S. Carr, Edmonton, Alta., one each in the Museum of Comparative Zoology 

 at Cambridge, the collection of the Boston Society of Natural History, the 

 National Museum collection at Washington, the collection of H. C. Fall, and 

 seven in my own collection. 



A SYNOPTIC REVISION OF THE ANTHOMYIID GENUS 

 HYDROPHORIA ROBINEAU-DESVOIDY (DIPTERA). 



BY J. R. MALLOCH, 

 Urbana, 111. 



The species of this genus with the exception of subpelhtcens Malloch are 

 entirely black, with the tibiae yellowish in a few cases. The thorax is usually 

 distinctly trivittate, and the abdomen has a black dorsocentral vitta. With 

 the single exception of nigerrima Malloch the American species known to me 

 have the halteres with yellow knobs, and all have the arista distinctly hairy. 



There are, I consider, two genera included under this generic name, separable 

 as indicated in the first two captions of my key, but it is impossible for me to 

 decide with the data available to me what the correct generic names are. 

 Acroptena Pokorny is undoubtedly applicable to the group with hairy hypo- 

 pleura, this character being used in this key for the first time, but whether 

 Hydrophoria is synonymous or not I am unable to say as I do not have the 

 type species before me. My object at this time is to place before students of 

 the family data for the identification of their material in the composite group, 

 such being of more importance than the separation of the larger segregates. 



It is not at all improbable that some of the species recently described by 

 me from America will eventually prove to be the same as European species 

 previously described, but the species are so very similar that only a comparison 

 of European and American examples will suffice to decide their specific identi- 

 ties. Comparison of European examples of ruralis Meigen and suhpellucens 

 Malloch proves that they are very closely allied if not identical, but there are 

 some characters which do not agree entirely, and for the present I have decided 

 to consider them as distinct. 



The larvae, so far as I know, are aquatic, and the species are mostly northern 

 in their distribution, commonest in the northwest. 



Key to Species. 



MALES. 



1? Hypopleura with some long hairs on upper margin in front of spiracle .2. 

 Hypopleura bare 8. 



2. Halteres black; deep black species, with thorax and abdomen almost 



devoid of gray pruinescence; eyes separated by more than width across 

 posterior ocelli, the orbits each with a series of long hairs along the 



inner margin nigerrima Malloch 



Halteres with yellow or pale knobs; thorax and abdomen with gray pruin- 

 escence; eyes usually separated by less than width across posterior 

 ocelli 3. 



3. Basal segment of hypopygium with very many stout bristles which are 



November, 1920 



