62 NORTH AMERICAN DIPTERA. 



TABLE OF GENERA. 

 1. Proboscis sliort, protruding but little from the oral opening; e3'es bare 

 or pilose; two or three submarginal cells. Hirmoneuba Meigen. 



Proboscis long, directed backwards; antennas broadly separated; e3'os 

 bare; ovipositor of the 9 composed of two slender laniellas; three 

 submarginal cells present. . . Rhynchockphalus Fischer. 



20. MYDxVID^. 



Rathev large to very large, thinly clothed or bare, elongate 

 flies. i*«J"euration complicated, the basal cells long; the fourth 

 vein always terminating at or before the tip of the wing. 

 Antennae elongate, the third .joint flattened, with a terminal 

 lamella. Front excavated between the eyes. Ocelli wanting. 

 Proboscis short, with fleshy labella and withont palpi (in onr 

 species). Empodia very little developed, not pulvilliform. 



The family ^Mydaidte coinj^rises only about one hundred 

 known species, but among them are the largest of the order, 

 a few measuring two inches in length and rivaled only by the 

 Acanthomeridai among the other families of diptera. The 

 larvffi of species of Mi/das live in decaying wood, a*nd it is 

 probable that all the members of the family have similar 

 habits. They are known to be predaceous in some cases n})on 

 the larvie of beetles. The larvai of M. fidvl.j/es are nearly 

 two inches in length,' with swellings below the abdominal seg- 

 ments for locomotion ; the body is depressed and somewhat 

 widened, with the posterior extremity broader and obtuse. 

 The pupa of M. clavdtns has as its anterior end two strong, 

 sharp, outwardly curved hooks ; the flrst abdominal segment 

 has, on its anterior border above, a row of very long, erect 

 spines curved backward at the tip. Another series of spines 

 is situated on the anterior border of the last segment, and, on 

 the same segment tliere is a pair of hooks at the tip curved 

 downward. 



