AMERICAN MUTILLID.E. 279 



BRACHYCISTIS Fox. 

 The two species herein, considered as females of this group, differ 

 from the males in having a two-spurred medial tibia. It is there- 

 fore not certain that these are really the female of Brachycistis, 

 inasmuch as in the other genera of the family the number of spurs 

 of the tibiae does not difier in the sexes. Nevertheless, it has been 

 thought advisable to keep the specimens in question in this position 

 until something definite may be learned of their habits, etc. Should 

 they prove not to be Brachycidis, then that genus is the only one 

 of the North American Mutillidse, of which but one sex is known. 

 To be sure, Mr. Ashmead has already characterized the female of 

 this genus as having a one-spurred medial tibiae, but he does not 

 state on what species this assertion is based ; so I take it for granted 

 that the genus was not known to him in the female sex, and that 

 the characterization in question was put forth hypothetically. 



MALES. 



First abdominal segment elongate, drawn out anteriorly into a slender neck. . .2. 



First abdominal segment short, generally sessile with second, not drawn out into 



a slender n&ck anteriorly 14. 



2. Head very small, narrower than thorax; form unusually slender; first seg- 



ment almost linear ampla Blake. 



Head at least as wide as thorax; form more robust; first segment varying 

 from a slender, elongate form to almost campanulate 3. 



3. Marginal cell nearly as long as the stigma idotes Ckll. 



Marginal cell much sliorter than stigma, not more tlian half as long at the 



most 4. 



4. First segment elongate, its width at ai)ex not by any means as great as half its 



length 5. 



First segment sliorter, broad at apex, which width is equal, or nearly so, to 

 half the lengtli of the segment 10. 



5. Thorax and abdomen entirely castaneous 6. 



Thorax and abdomen black or quite dark 8. 



6. Head scarcely narrowed behind, concolorous with tliorax (second submarginal 



cell variable) nitida Cress. 



Head black 7. 



7. First segment slender, at least one quarter longer than second ; abdomen not 



hirsute; thorax, abdomen and legs dark castaneous; head considerably 



narrowed behind eyes iiudiis n. sp. 



First segment stout, not one-quarter longer than second, abdomen sparsely 

 pubescent; thorax and abdomen light castaneous, legs testaceous; 

 antenna; orange; head but little narrowed behind eyes. 



elegaiitiilns Ckll. 



8. Stigma of wings pale yellow ; legs, except coxse. mandibles and antennse, yel- 



lowish ; thorax brownish or wine colored petiolatlis Fox. 



TRANS. AM. ENT. SOC. XXV. M.AKCH, 1899. 



