2 
The Ohio Naturalist. 
[Vol. IV, No. 1 , 
parts. The ventral space is quite evidently divided into two equal 
parts by a longitudinal grove. In order to see the characters of 
this segment it must be fully extended. The mesothoracic and 
metathoracic segments have a number of longitudinal grooves, 
some of which are very narrowly bordered by opaque darker col- 
oring, which proceeds backward from the narrow anterior border 
of these segments. Each of the first seven abdominal segments 
has on its anterior part a transver.se row of eight tubercles which 
encircles the segment. These all bear spines or claws at the 
apexes, excepting a dorsal pair on each of the first three or four 
segments. They may be called prolegs, since they have the parts 
necessar}’ to such organs. On the posterior dorsal border of most 
of the abdominal .segments there ma}' be a narrow, irregular, 
oj)aque marking of the same color of the narrow band in the 
region of the prolegs ; eighth segment on each side with two nar- 
row, curved markings, which have the appearance of being com- 
posed of contiguous punctures. These markings are of the same 
shade of color as the other darker areas, and the lower one is more 
than twice as long as the upper. 
Length, 20 millimeters. The size of these lar\-ae is rather diffi- 
cult to give, since a specimen fully extended is longer than at 
other times. 
Pup.v. — Length 18, diameter 4 millimeters. Light brown in 
color, thorax somewhat paler than the abdomen. Antennal and 
other tubercles of the head and thorax prominent and darker than 
the surrounding parts. Prothoracic spiracular tubercle slightly 
elevated, reniform, oblique ; rima uniformly curved for nearly its 
whole length, but just before the anterior end the curvature is 
stronger but no hook is formed. First abdominal spiracle nearly 
round ; rima nearh’ uniformly curved, posteriorly ver}' slighth' 
widened just at the end, anterior!}- slightly narrowed and curved 
so as to form a short hook. The other abdominal spiracles agree 
with the first one in general, but there appears to be .slight varia- 
tion in the enlargement and curvature of the extreme ends. Ter- 
minal teeth prominent, shining brown in color, darkest at the 
extreme tips. Dorsal pair of teeth smallest and closer together 
than the ventral, lateral teeth longer and larger than the ventral 
and located much beneath the dorsal, in fact they are nearly mid- 
way between the dorsal and ventral. 
I have never found the adults of this species especially com- 
mon, neither have I observed that they molest stock. The male 
has been procured fully as often as the female on protruding 
stones in swift-flowing streams, and in sunny spots in woods near 
such streams. Most of the specimens in my collection were taken 
during the first half of June. 
All the stages of this fly have been procured from the Scioto 
River in the vicinity of Jones’ Dam, near Columbus. 
