106 Annals Entomological Society of America [Vol. IV, 



Below, pale whitish yellow, mesonotum margined at the apex with a 

 transverse band of brown. Pleurae and coxal areas pale with irregular 

 shadings of dark brown. Legs whitish; coxae with dark brown spot; 

 femora with conspicuous brown spot and a brownish band just before 

 the apex; more distinct on the anterior legs; tarsi with flap and claw 

 similar to that of Iron fragilis (PL X, fig. 3) and identical in all three 

 legs. Wings hyaline with the humeral cross vein blackish brown (in all 

 adult stages). Abdomen, pale whitish, translucent on segments 2-5. 

 Tergites with distinct transverse brown pencilings on their posterior 

 borders and a median broken line of brown more distinct on the posterior 

 portions of the tergites. Sternites pale without markings. Forceps 

 pale, (PI. IX, fig. 2). Setae whitish. ' ' 



Female sub-imago. General color of the body slightly darker than 

 that of the imago. Abdomen darker, less translucent. Wings grayish, 

 sub-hyaline. Thorax with markings less sharply denned and general 

 color darker than that of the imago. Abdomen with the tergites suf- 

 fused with brownish. 



Female imago. (Live specimen). Forelegs shorter than those of 

 the male. In specimens containing eggs the abdomen is a bright salmon 

 pink, which does not fade readily in alcohol. Head, with eyes similar 

 to those of the male, but smaller and distant being separated by a broad 

 unmarked portion of the occiput. The dark bands of the ocelli are in- 

 complete and a trifle narrower than those of the male. Thorax, with 

 the pronotum exposed showing the prominent median indentation of its 

 posterior margin; an area on either side the median line with a longitudi- 

 nal blotch of brown. Abdomen with the tergites slightly darker brown 

 than in the male. Sternite 7 prolonged two thirds the length of sternite 

 8. Sternite 9 slightly shorter and but shallowly notched on its posterior 

 border. 



Nymph. (PI. IX, fig. 1). Body depressed, widest across the meso- 

 thorax gradually tapering to the last abdominal segment. Nymph 

 larger and broader than Iron fragilis with its lamellae flaring; the lamel- 

 lae of the first and last pairs of gills distant from one another and the 

 traeheation of the lamellae conspicuous. Posterior lateral angles of the 

 abdominal segments produced into backwardly directed spines which 

 guard the bases of the lamellae (PI. IX, fig. 1). Color, olive-greenish 

 blotched and shaded with brown, pale below. Head with eyes and 

 ocelli prominent, the latter with dark lunate bands on their inner margins. 

 Antennae slender and bare. Lateral margins of the prothorax rounded 

 anteriorly, and flaring. Legs flattened with a row of rather long 

 soft hairs on the posterior margins of the femora and tibiae. General 

 shape conical, rounded above, slightly flattened below. Gill lamellae 

 obliquely reclinate with fasciculate filaments on the dorsal side of their 

 bases. Setae 2, about as long as the body. 



Baetinae. 



This heterogenous group was represented in the summer's 

 collecting by Blasturus cupidus, Leptophlebia praepedita, 

 Leptophlebia mollis, Choroterpes basilis, Callibaetis fluctuans, 



