1911 1 Aldrich — North American Species of Hydrophorus 49 



(fig. 10 breviseta Thomson. 



Front tibia not notched 11 



11. Size 3 mm.; pleura with rather thick white pruinosity sodalis Wheeler. 



Size 4.5 mm.; pleura with thin yellowish pruinosity. . . magdalenae Wheeler. 



12. Wing with a brown spot on the middle of the last section 



of the fourth vein, and another on the hind crossvein (fig. 2) 1 



Wings without these spots 18 



13. Face opaque non-metallic 14 



Face showing some metallic color 17 



14. Face brownish-yellow, a gray spot on each side below. . . .signiferus Coq. 

 Face not so marked 15 



15. Front coxae with black bristles on the front side besides those at 



tip 16 



Front coxae with no black bristles except at tip cf algens Wheeler. 



16. Wings with the spots distinct enough to see with the naked eye.chrysologusWlk 

 The spots only faintly visible with a lens pirata Loew. 



17. With a black propleural bristle 9 algens Wheeler. 



With a pale bristle or stout hair phoca sp. nov. 



18. Face wholly opaque 19 



Face showing some metallic color 20 



19. Front coxa with a row of black spines in front, longest above, run- 



ning out apically parvus Loew. 



Front coxa with a row of spines, longest toward the tip, rimning 



out proximally pirata Loew. 



Front coxa with no spines except at tip extrarius sp. nov. 



20. Front coxae with long and striking spines on the basal part in 



front innotatus Loew. 



Front coxae with no spines on basal part in front 21 



21. Cheeks projecting downward in a small lobe below the eye 



altivagus sp. nov. 



Cheeks not forming a lobe below the eye, very narrow 22 



22. Male with a protuberance preceded by a tuft of small spines on 



the under side of front femur near tip (fig. 13) amplectens sp. nov. 



Male without such structure 23 



23. Upper part of the face bright blue-green pensus sp. nov. 



Upper part of face dull, only a little greenish extrarius sp. nov. 



DESCRIPTION OF SPECIES. 



(Made with Zeiss binocular dissecting microscope, 30 diameters.) 



Hydrophorus gratiosus sp. nov. 



Male. Occiput bluish-green above, with moderate whitish pruinosity; post- 

 vertical bristles rather close together, with about four bristles each side, forming a 

 row that joins the postorbitals both ways; the latter extending below the middle 

 of the eye, beard whitish, a few stiff black spines showing just below the neck; 

 front with dense brown pruinosity, not shining; face dirty whitish pruinose, not 

 shining, of medium width; palpi of moderate size, black in ground color, opaque 



