230 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



... 



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43 (42). Proboscis short ; abdomen flattened Ploas Latr. 



44 (23). Three posterior cells; anal cell closed : 



45 (46). Proboscis much longer than the antennae;- small, Bombylius-\ike, 



pubescent insects Geron Meig. j 



46 (45). Proboscis shorter than the antennce; long, Sjphex-like, almost 



glabrous insects; abdomen with the four basal joints very 

 narrow Systropus Wied. 



EXOPROSOPA. 



I have tried to construct an analytical table for all the described 

 species from the United States. In using it, it must be borne in mind 

 that E. gazophylax Lw., btfurca L., and agassizi Lw.,*I know only from 

 the descriptions. All the species except E. gazophylax have three pos- 

 terior cells. 



1 (2). Style of the third antennal joint not more than one-fourth the 



length of that joint P' f asciata Mac ^ 



( 2. siman. sp. 



2 (1). Style of the third antennal joint very long, from one-third to one- 



half as long as the joint, or more : 



3 (14). The expanded end of the marginal cell is not altogether hyaline 



(more or less filled out with brown) : 



4 (9). The marginal cell is altogether brown (except a small subhyaline 



spot in its proximal third) : 



5 (6). Four submarginal cells .3. gazophylax Lw. 



6 (5). Three submarginal cells : 



7 (8). Proximal half of the wings altogether brown 4. decora Lw. 



8 (7). Proximal half of the wings brown, but with a hyaline cross- 



band . , , . « 5. dorcadion n. sp. 



9 (4). The marginal cell contains one or more hyaline spots : 



10 (13). The marginal cell contains one hyaline spot before its expanded 



distal end, cutting off a brown spot which fills out that end: 



11 (12). Both brown cross-bands fully reach the posterior margin, 



5. dorcadion var. 



12 (11). ^Neither of the two cross-bands reaches the posterior margin, 



7. fascipennis Say. 



13 (10). The marginal cell contains three large hyaline spots, alternating 



with brown ones , 6. caliptera Say. 



14 (3). The expanded end of the marginal cell is altogether hyaline : 



15 (So). Whole marginal cell brown, except its expanded end: 



16 (17). Prevailing color of the wings brown, except the apex and a 



large spot in the discal cell, which are hyaline, 



8. emarginata Macq. 



17 (16). Prevailing color of the wings hyaline: 



18 (19). Cross-veins at the base of the third and fourth posterior cells 



strongly infuscated . '. 9. titiibans n. sp. 



19 (18). Cross-veins, etc., not infuscated. . . .. 10. dodrans n. sp. 



