422 NEW YORK STATE MUSEUM 



1885 Baetis pygmaeus Eaton, Linn. soc. Lond. Trans. (2) 3 : 170 (a new 



description of the fragments remainiug of the type) 

 1892 Baetis pygmaea Banks, Am. ent. soc. Trans. 19 : 348 (listed) 



All the above are bare descriptions of the single female specimen in 

 the Hagen collection from the St Lawrence river. 



I studied this fragmentary type specimen in Cambridge Aug. 25 and 

 28. There remains of it a bit of the thorax, bearing the greater part of 

 one fore wing. The venation of this wing furnished the only points for 

 critical comparison with my specimens. The descriptions and the type 

 specimens agree fairly well with the smallest of my specirriens. I could 

 not see the brownish color of the veins described by Eaton either in my 

 specimens or in the type. Also the veins in the pterostigmatic space 

 vary in number in my specimens from 5 to 12, and from being simple 

 and straight to being forked and anastomosing. 



This species, like the preceding, was common in the hatchery 

 windows, was taken often sparingly in the trap lanterns, and was seldom 

 seen at large. Images occurred more sparingly, however, through the 

 earlier part of the season, but they became very abundant in August. 

 From the window in the hatchery nearest the mouth of the inflow pipe 

 carrying surface water, hundreds of imagos and subimagos could be 

 picked at a time. These were preyed on in great numbers by spiders 

 which lurked in the crevices of the window casings. Not a few flew 

 against the window panes when these were wet with condensations in 

 the mornings, and, striking their wings, adhered, and were unable to 

 free themselves. When the moisture evaporated, these were dried down 

 on the glass. Among these I noticed a number of females which had 

 discharged the contents of their ovaries on the pane in masses of about 

 200 eggs each. 



Nymphs of this species were found most abundantly among the cases 

 of Simulium pupae in swiftly flowing water; a few could be taken at any 

 time from the hatchery troughs. 



This is the daintiest, and one of the prettiest of our May flies. It is 

 still so insufficiently known that I will append hereto complete descrip- 

 tions of the stages known to me. 



Male imago. Length 3-5 mm; setae 7 mm additional. Colors 

 black and white varied with reddish brown and yellowish red. Head 

 yellowish, with the ocelli and the inferior part of the eyes black, turbi- 

 nate superior part of the eyes yellowish red on the sides, reddish brown 

 on the superior, corneal surface. 



Thorax black, paler on the lateral sutures. Legs, antennae and setae 

 pale yellowish white ; fore legs darker on the sutures. Wing very trans- 

 parent with a faint wash of yellow on the extreme base. Hind wing 

 bivenulate, sometimes with a short third vein. 



