emery: simulium vittatum in Kansas. 353 



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 



IC. Metallic bluish black species; middle portion of fore tibiae, base 

 of middle and hind tibite, base of first and second joints of mid- 

 dle and hind tarsi, whitish. Length 2 mm metallicmn 



Thorax fuscous and cinereous poUinose; the humeri pallid, fore 

 coxas pale, middle and hind ones dark; femora pale at the base, 

 black at the tip; tibiae black. Length 3 mm cinereiun 



17. An oblique metallic streak extending inward from each humerus; 



posterior part of the thorax metallic. Length 2 to 2.5 mm. 



venustum 

 Humei-al spots not metallic IS 



18. Anterior coxje yellow; long hair on femora and hind tibiae; thorax 



velvet black with white pruinose margin (Greenland) . .reptaiis 

 Anterior coxae black 19 



19. Thorax velvet black, with oblique cinereous humeral spots, and 



usually two tiny metallic spots between them. Length 3 to 4 mm. 



pictipes 

 Thorax velvety black with two very narrow gray stripes and pos- 

 terior margin; hind tibise usually yellow at the base, hair on legs 

 sparse vittatum 



20. Thorax striped 21 



Thorax without stripes 25 



21. Dorsum of thorax with four longitudinal lines, posterior margin, 



white pollinose; abdomen opaque black. Cuban species. 



quadrivittatum 

 Not with four stripes 22 



22. Dorsum of the thorax with five stripes, the outer ones spot-like, 



the intermediate ones clubbed at the ends; abdomen with black 

 fascia on each segment, produced posteriorly at the middle and 

 the ends. Sometimes the last few segments have only three or 



five spots vittatum 



Toe with one or three stripes 23 



23. With three stripes 24 



"With an indication of a darker median vitta" (see 31) . .griseum 



24. Small species, length about 1.5 mm. "Abdomen silvery, third and 



fourth segments wholly brownish, sometimes with a median spot 

 on each; legs yellowish, tarsi blackish or brownish." Species 



from Texas tamaulipense 



Laiger species 3 mm. or more in length 24a 



24a. Middle tibise brown with a yellow ring around the base; vitt» of 

 mesonotum brownish, the median vitta dilated posteriorly, wider 



than either of the lateral ones. New Mexico virgatum 



Femora and tibiae grayish, sometimes quite pale, tips of tibiae 

 black. Laterdorsal thoracic stripes clubbed at the anterior end. 

 Third, fourth, fifth, and part of the sixth and seventh abdominal 

 segments with velvet-black fasciae; center of 6, 7, 8, grayish or 

 dull brown pictipes 



