168 MEDICAL ENTOMOLOGY 



5- Body black ; the female with dense yellow pile, her tarsal 

 claws simple ; the male with dense hair on the legs, his 

 tarsal claws trifid. The wing with its radius three branch- 

 ed. Length 3 to 4. 5 mm . . hirtipes. 



' Body grey, legs reddish grey, feet black ; length 3 mm '. This 

 is said by Mr. Coquillett to be the same as pecuarum, 



Riley inveiiustum. 



6. Males, eyes contiguous ........ 7 



Females, eyes separated by a distinct line ....... 8 



7. Thorax velvety black ; legs reddish with black tarsi. Length 



1. 5 to 2 mm. Compare here also bracteatum (male) ' with 



legs wholly brown ' meridionale. 



Thorax brownish black ; legs usually pale ; tip of tarsi not 



black. Length 2 to 4 mm pecuarum. 



8. Thorax with silvery white pubescence ; legs brownish black, 



covered with whitish hairs. A small variety (less than 

 2 mm. long), from New Mexico has been named occidentale, 



Townsend meridionale. 



Thorax with yellow hairs ; legs reddish brown, covered with 



yellow hair ; tip of tarsi blackish ...... pecuarum. 



9. Males, eyes contiguous ........... 10 



Females, eyes separated ........... 20 



10. ' Mesonotum wholly velvet black ; grey spot on sides of the 



second, fifth, sixth and seventh segments of abdomen. 



Length 1.5 mm.' bracteatum. 



Metanotum striped, or with greyish or metallic reflections .... 11 



11. Dorsum of thorax with one or more longitudinal stripes .... 12 

 Dorsum unstriped 14 



12. Thorax with four longitudinal stripes ; posterior margin white; 



abdomen black. Sex not given. Cuban species . . . quadrivittatum. 

 Thorax not so marked ........... 13 



13. Front and middle femora and tibiae wholly yellow ; centre of 



mesonotum with a black vitta, elsewhere grey. Length 



1'5 mm. Colorado Species ....... griseum. 



Femora and tibiae wholly or partly brown ....... i8a 



13a. ' Femora and front tibiae yellow, their apices brown ; middle 

 tibiae brown, a yellow ring beyond the base, hind tibiae 

 brown, the extreme base yellowish. Mesonotum marked 

 with a narrow median and laterally with a very broad velvet 

 black fascia. 1 Length 3 mm. New Mexico . . . virgatum. 

 Front femora brown, tibiae brown on apical part . .... 18ft. 



13 b. Mesonotum with two narrow grey stripes (sometimes quite 

 indistinct) on a velvet black ground, in which there are 



scattered golden hairs vilt alum. 



1 Mesonotum marked with a narrow median and slightly wider 



lateral black vittae.' Length 2'5 mm. Missouri . . glaucum. 



14. Anterior femora yellow. Mexican species ....... 13 



Anterior femora black 17 



15. Abdomen with the base of the second segment, and the sides 



of the third, fourth, and fifth yellowish white, tibiae fuscous 



black with yellow bases. Length 4 mm mexicanum. 



Abdomen black ... 16 



