Fig. 27. 
Fig. 28. 
Fig. 29. 
Fig. 30. 
Fig. 31. 
BURROWING MAYFLIES. 291 
PLATE LXXV. 
Ephemera varia Eaton; adult. 
The adult male. 
The legs of one side of the same. 
The end of abdomen of the same from beneath. 
PLATE LXXVI. 
Ephemera varia Eaton; nymph. 
The nymph from above, gills on the right tured aside to show normal color pattern. 
Head of same, more enlarged. 
Figs. 32, 33, 34. First, middle, and hind legs, respectively. 
Fig. 35. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
39° 
A gill from the second abdominal segment. 
PLATE LXXVII. 
Polymitarcys albus Say; adult. 
Adult female, hovering with egg packets extruding. 
The legs of one side, adult male. 
End of abdomen of male from below, showing strongly divaricate penis tips. 
PLaTE LXXVIII. 
Polymitarcys albus Say; nymph. 
The nymph from above. 
Head of the same, more enlarged. 
Mandible of the same. 
Maxilla of the same. 
Labium of the same. 
Fore leg of the same. 
A gill of the second abdominal segment. 
PLATE LXXIX. 
Euthyplocia sp.? nymph. 
The nymph from above. 
Head of the same, more enlarged. 
Mandible of the same, hairs of the tusk omitted. 
Maxilla of the same. 
Labium of the same. 
A gill of the second abdominal segment. 
PLATE LXXX. 
Potamanthus flaveola Walsh; adult. 
The adult female. 
The legs of one side of the adult male. 
The ventral aspect of the male genitalia, showing the form of forceps and penes. 
PLATE LXXXI. 
Miscellaneous (figs. 55, 56, and 57 by Dr. Anna H. Morgan). 
The venation of the wings of Ephemera. 
Vein designations are those used in accompanying key; the six principal veins are: C. costa, 
Sc. subcosta, R. radius, 4. media, Cu. cubitus, A. anal vein. 
Branches of veins are marked with small numerals, in order from the front. The posterior 
fork of the median vein is the one in which veins M, and M, unite. R, is the radial 
sector; 1 is the principal accessory vein. The third anal vein is the forked vein behind 
the second anal. 
