40 THOMAS SAY FOUNDATION 
as far from each other as from the inner margin of the compound 
eyes; front ocellus only indicated by a small depression ; surface 
smooth, with a feeble coating of fine hair; antennae light brown 
in color, of fifty or more segments. 
Pronotum about twice as wide as long; front and hind margins 
nearly straight, much widened posteriorly; hind angles very 
broadly rounded; front angles narrowly rounded; surface smooth 
and densely coated with hairs, the postero-lateral angles with 
branches of long hairs; the marginal groove in this species repre- 
sented only back of the anterior margin; meso- and metanotum 
longer than the pronotum, and slightly wider; surface smooth, 
but with a general coating of fine hairs, and with longer spine- 
like hairs on the lateral margin, as well as on the surface toward 
the lateral margin. 
Legs broad, short, and spiny; the coxa broad, and the outer 
areas produced into a rounded lobe margined with long hairs, 
the inner part of the coxa bears on the distal end a row of long 
spines, and another shorter row of spines farther back ; trochanter 
somewhat triangular, with a row of spines at the distal margin ; 
femur about half as wide as long, on the inner margin with a 
deep groove; on the outer margin with a fringe of hairs, and on 
the surface with numerous short hairs and spines; tibia a little 
shorter than the femur, with many short spines, and on the outer 
margin with a fringe of long hairs; first two segments of tarsi 
short, subequal, and the two together less than one-half as long as 
the third. 
Abdomen flattened; all except the last four or five segments 
usually covered with the large metanotum; posterior margin of 
the abdominal segments with a fringe of spines which are espe- 
cially long on the last segment; cerci rather stout at the base, 
gradually tapering to a slender point and made up. of about 
twenty-five segments. 
The pro-, meso- and metasterna developed into large flat 
shields. 
The five pairs of filamentous gills are located as follows: two 
pairs at the outer base of the mesothoracic leg almost completely 
covered by the mesonotum; two pairs on the metathorax; and 
one pair on the underside of the metasternum, located at a 
point half way between the base of the leg and the postero-lateral 
angle. 
This species occurs in the Eastern States where the nymphs may 
be found in small spring brooks among the leaf drift and debris. 
Many reared nymphs from Ithaea, N.Y. 
