F. R. COLE 49 



simple auxiliary near the costa, a long first longitudinal from which 

 the praefurca issues before the middle of the wing. The second 

 longitudinal, when present arises near the praefurca, but it is 

 indicated by a rudiment in some and in others is obliterated. The 

 open fork in the tip of the wing is composed in the upper part of 

 the end of the third vein, and in the lower by an end piece of the 

 fourth vein; below this are two simple long veins (lower branch 

 of fourth and fifth), and these veins are connected by a long ap- 

 parent cross-vein between the third and fourth vein and another 

 between the fourth and fifth vein. The anal vein is simple and 

 straight. There is no trace of the discal cell; the posterior veins 

 hardly reach the wing margin. If the cell which includes the 

 wing tip is included, there are three posterior cells in all. Alulae 

 large. Squamae very large, bare, and of apparently thinner tex- 

 ture than in Og codes. Alar squamae small. (The above is essen- 

 tially the description given by Verrall in his British Diptera.) 



The wing venation is variable and very puzzling in some cases, 

 and it requires a great deal more material to settle certain points. 

 Westwood's short Latin descriptions are far from adequate, now 

 that so many species have been described. Ho far as known the 

 species of this genus parasitize ground spiders such as Lycosa and 

 Afnaurobius. 



Synopsis of Species 



1. Dorsum of thorax marked with yellow 2 



Dorsum of thorax without yellow markings 3 



2. Thorax with a median black stripe and two elongate spots on either side. 



liturata W'illiston 

 The lateral stripes of dorsum much larger, reaching tlic black scutellum. 



subfasciata Westwood 



3. Second vein present and other veins as in typical form 4 



Venation not typical 7 



4. Abdomen largely yellow or n^ddish 5 



Abdomen mostly black tj 



5. Base of abdomen l)lack, the foiu- corners of thorax whitish. 



bakeri Cotiuillett 

 Base of abdomen yellow, the four corners of thorax black. 



bakeri var. arizonensls new variety 



6. Praescutellar callosities mosth' black and the rims of sciuamae l)lack in 



females bulla ^\'estw()od 



Praescutellar callosities mostly white, rims of squamae whitish. 



bulla var. melanderi new variety 



TRANS. AM. ENT. SOC, XLV. 



