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 nuist be fully extended. The mesothoracic and 

 metathoracic segments have a number of longitudinal grooves, 

 some of which are very narrowl}' 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 transverse 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 

 necessary to such organs. On the posterior dorsal border of most 

 of the abdominal segments there may be a narrow, irregular, 

 opaque 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 larvae is rather diffi- 

 cult to give, since a specimen fully extended is longer than at 

 other times. 



Pupa. — lycngth 18, diameter 4 millimeters. lyight 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 nearly uniformly curved, posteriorly very slightly 

 widened just at the end, anteriorly 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 uearl}- 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 Jmie. 



All the stages of this fly have been procured from the Scioto- 

 River in the vicinity of Jones' Dam, near Columbus. 



