AQUATIC INSECTS IN THE ADIRONDACKS 42I 



were snapped up eagerly by the trout. The membrane of the wings of 

 the imago is in this species finely iridescent. 



Nymph. PI. 15, fig. 16 Length of body 10 mm; setae, male 12, 

 female 15 additional; abdomen, male 6.25, female 7. 



Body flat; lateral margins of the head and prothorax thin, sharp 

 edged, flaring, that of the head projecting distinctly beneath the eyes, 

 antennae reaching the tips of the extended fore femora; all femora 

 flattened, sharp edged, edges very convex and fringed with hairs. 



Color yellowish or greenish brown, motded, paler below, and dorsally 

 marked with paler spots as follows : an inverted, mushroom-shaped spot 

 before the middle ocellus, a triangular patch between each reniform, 

 lateral ocellus and the eye, a transverse band at the rear of the head; 

 an oblique band each side of the prothorax, a large lateral spot each side 

 of each of the intermediate abdominal segments with a black mark at 

 its hind margin. The femora and tibiae show very indistinct transverse 

 banding of color. 



Abdomen with sharply toothed posterolateral angles on its hindmost 

 segments, the tooth largest on the eighth segment, where it surpasses the 

 middle of the ninth segment, smaller on the seventh and ninth, and a 

 mere sharp angle on the sixth segment. Setae sparsely fringed with hairs 

 for a third of their length. 



Gills present on segments 1-7, similar on 1-6, though becoming 

 smaller posteriorly. Anterior gills double, the anterior leaf thickened, 

 trapezoidal with the angles all obtuse, a sparse fringe of slender hairs 

 around the distal half of its border, a strong obUque, longitudinal ridge 

 on its anterior face near its ventral edge ; posterior leaf thin and deli- 

 cate, covered by the anterior, smaller than the anterior, cordate 

 triangular in general outline, cut into a peripheral fringe of long 

 respiratory filaments which are once or twice forked or simple, the fringe 

 being as long as the body of the leaf. Gill of the seventh segment 

 simple (corresponding to the anterior leaf only), lanceolate, fringed 

 along its entire margin, its apex surpassing the lateral tooth of the 

 eighth abdominal segment. 



This species is known from Rock Island 111., Maryland, New York 



and Quebec. 



There is in the Museum of comparative zoology a specimen of another 

 species labeled "Adirondacks, New York, Aug. 1872" in Dr Hagen's 

 handwriting, which agrees entirely with other specimens in the same 

 museum bearing the name Heptagenia vicaria Walker. 



Baetis pygmea Hagen 



Plate 15, figures 13, 14 



1861 Cloe py gm e a Hagen, Synopsis Neur. N. Am. p. 54 (original descrip- 

 tion) ,. 



1863 Cloe pygmaea Hagen, Ent. soe. Phil. Proc. 2 : 178-79 (notes, "It is 

 the smallest epbenierous species known.") 



1871 Baetis pygmaens Eaton, Ent. soc. Loud. Trans, p. 122 (original 

 description, repeated in Latin) 



