216 NEW YORK STATE! MUSEUM 



number of cross veins in any part, but in general they are more 

 numerous in the female. Behind the costal brown band in the 

 female there are about 70 cross veins, not in a single row, not in 

 regular rows at all. 



Abdomen pale yellowish or flesh tinted, thickly dotted and 

 dj>8hed with brown, tending to form a dark middorsal band, more 

 or less completely divided on the base of each segment, a line of 

 brown dashes each side just above the pale lateral margin on 

 segments 1-9, with a more or less separate curved mark above 

 the anterior end of each dash. At the sides the metathorax 

 overlaps the first abdominal segment and almost reaches the 

 base of segment 2. The ventral side of the abdomen is paler with 

 more uniform dots and a pair of submedian brown ()- marks 



Fig. 2 End of abdomen of Callibaetis skokiana, male, central view, showing 

 forceps, rudimentai-y median caudal fllament and bases of latei-al filaments 



on segments 2-9, abbreviated on segment 9. Forceps of the 

 male [figure 2] and setae of both sexes pure white. 



Subimago. Differs in having the setae shorter (about 9mm 

 long in both sexes), the wings faintly smoky brown, or slightly 

 tinged with yellowish on the middle of what is to be the costal 

 band, and the principal bands of brown on the body faintly indi- 

 cated. 



Nymph. Length of body 12-13mm, setae 6-7mm additional; 

 width of head 1.2mm, of thorax 1.8mm. Color greenish, marked 

 with pale fuscous. 



Head pale, suffused with brownish around the eyes and across 

 the ocelli in front, a longitudinal band bounding each eye inter- 

 nally, tinged with yellowish. 



Prothorax pale marked with fuscous on the front margin and 

 at the sides, with a pair of pale spots in irregularly contoured 

 brown inclosures on the dorsum. Mesothorax and metathorax 

 darker dorsally with pale markings at the front margin and at 



