FAMILY EPHYDRID.E THE SHORE FLIES 349 



9. Wing-s with a strong fold extending the length of the discal cell near 



the mitldle antl another in the apical cell (21, 49) . .Clanoneurum Becker 

 Wing-s without such folds 10 



10. Arista without rays below '. 11 



Arista with two or three rays below (38, 44) Ptilomyia Coquillett 



11. Face with transverse ridges, at least laterally, which may be very 



bi-oad, or fine and numerous, usually limited to the lower half of 



the face 12 



Face without such ridges 14 



12. Facial ridges very fine, extending across the face, sometimes not con- 



tinuous on the lower part (58, 66) Leptopsilopa Cresson 



Facial ridges very broatl 13 



13. Facial ridges strong, extending across the face (68) .Cerometopum Cresson 

 Facial ridges resulting from sub-lateral pits and not extending over 



the middle of the face (37, .52) Discomyza Meigen 



14. With only one pair of dorsocentral bristles 21 



With two pairs cf dorsocentrals 15 



15. Ocellar bristles widely separated, situated opposite the anterior ocellus. 16 

 Ocellars normal, situated above the anterior ocellus 19 



16. Bristles on the sides of the face all convergent 17 



Bristles on the sides of tl\e face partly tlivergent, partly convergent. 



Polytrichophora Cresson 



17. Face with two rows of bristles on either side 18 



Face with one row of bristles on either side (10, 56) .Discoceriaa Macquart 



18. Posterior tibite with a strong, curved apical spine (31). 



Hecamedoides Hendel. 

 Posterior tibise without apical spine Diclasiopa Hendel 



19. Interfrontalia with two pairs of bristles (67, 72) Paratissa Coquillett 



Interfrontalia without bristles, the ordinary frontals present 20 



20. Face rather strongly carinate above, the carina ending prominently at 



the middle of the face (41, 63) *Ilythea Haliday 



Face very gently convex longitudinally, not carinate (Typopsilopa 

 Ciesson ) ( 54 ) Psilopina Becker 



21. Oral opening large, the clypeus always prominent, the middle of the 



face usually strongly produced 22 



Oral opening smaller, the face usually convex antl receding below, the 

 face never strikingly produced in the middle 24 



22. Third costal section longer than the second (19) Atissiella Cresson 



Third costal section shorter than the second 23 



23. Ocellars inserted opposite the anterior ocellus (45) Atissa Haliday 



Ocellars inserted above the anterior ocellus (9) . . . . Allotrichoma Becker 



* Cresson. 1918, Trans. Amer. Ent. Soc, xliv, p. 50 (Costa Rica). 



