522 LIST OF DIPTEBA. 



B. Corpus plus minusve metallicum. 



A. Nigro-caerulescens. ... melanogaster, Wied. 



B. Nigro-viridis. Abdomen nigro-caerulescens. pygmaea, Macq. 



C. Nigro-aenea. 



a. Alae subfuscae. - Alcanor, Walk. 

 B. Ala3 limpidse. 



a. Tibiae uon clavatae. - - - Sacrator, Walk. 



b. Tibiae posticae clavatEe. ... Ecbemon, Walk. 



The North American species comprise the following groups. 



Group 1. 



Corpus pilosissimum, sat gracile. Facies apud epistoma con- 

 vexa. Mystax setis plurimis longis. Proboscis recta, linearis. 

 Antennarum articulus 3us longifusiformis, lo et 2o conjunctim 

 multo longior. Pedes validi, hirsutissimi ; femora crassa. 



Body very hairy, rather slender. Face convex towards the 

 epistoma. Mystax with long and very numerous bristles. Proboscis 

 straight, linear. Third joint of the antennae elongate-fusiform, 

 much longer than the first and the second together. Legs stout, 

 very hairy ; femora thick. Fore fork of the cubital vein slightly un- 

 dulating; hind fork and the first esterno-medial very slightly 

 curved, parallel to each other ; second externo-medial straight, 

 third forming an obtuse angle with the praebrachial, joining the 

 fourth far from the border. Subanal united to the anal very near 

 the border. 



Laphria iEatus. 



Group 2. 



Corpus pilosissimum latiusculum. Facies apud epistoma sub- 

 convexa. Mystax setis plurimis longis. Proboscis recta, linearis. 

 Antennarum articulus 3us linearis, gracilis, articulis lo et 2o con- 

 junctim multo longior. Pedes validi, hirsutissimi ; femora crassa. 



Body very hairy, rather broad. Face slightly convex towards 

 the epistoma. Mystax with long and very numerous bristles. 

 Proboscis straight, linear. Third joint of the antennae linear, slen- 

 der, very much longer than the first and the second together. Legs 

 stont, very hairy; femora thick. Wing-veins like those of the first 

 group. 



Laphria tergissa, L. posticata, L. thoracica, L. sericea, L. Sacrator, 

 L. lasipes, L. Alcanor. 



