1893.] NATURAL SCIENCES OF PHILADELPHIA. 381 



dark blue or black with a metallic reflection, tborax almost entirely 

 pruinose, yellow markings obliterated. 



Legs brown, paler inferiorly, yellow at bases (teneral) ; darker, 

 somewhat pruinose (adult). 



Abdomen rather slender. Teneral: brown; base of 1 yellowish 

 on dorsum ; 3-9 with a transverse, basal, yellow ring, interrupted 

 on the middle line on 3, on 9 very small and connected by a mid- 

 dorsal line with a larger apical, yellow spot ; greater part of dor- 

 sum of 10 and a lateral stripe on 2 and 3 bright yellow. Adult: 

 black; yellow markings less distinct anteriorly, obliterated on 8-10, 

 dorsum of 9-10 pruinose. 



Superior appendages as long as 9, somewhat forcipated. Each 

 has on its upper outer margin, just beyond the middle, 5-6 small 

 spines; lower inner margin much dilated and with two teeth in the 

 apical half, the more basal of which is rounded and lies opposite 

 the spines of the upper margin, while the more apical tooth is 



Fig. 2. Profile view, appendages of O. clara $ 



smaller, somewhat triangular, its apex slightly notched ; beyond 

 this second tooth the remainder of the appendage, about one-sixth 

 of the entire length, continues as a cylindrical piece with a rounded 

 apex. 



Inferior appendages about half as long as the superiors ; viewed 

 from the side, each is rather thick at the base, becoming slender dis- 

 tally, with a small acute tooth near the middle of the upper margin, 

 apical half slender, curved upward, apex acute. Viewed from 

 below, the two inferiors are closely approximate in their basal 

 halves, the slender apical halves separated from each other at first, 

 converging posteriorly. 



Wings hyaline. Pterostigma and reticulation luteous (teneral) 

 or black (adult), the former surmounting 3-4 cells. 18-23 post- 

 cubitals on front wings, 15-19 on hind wings. 



9 similar in coloring to the teneral $ from which it differs as 

 follows: humeral stripe and that in front of the metastigma conflu- 

 ent at their upper ends, but with the spot of the reversed ! distinct ; 

 a short, oblique, isolated, brown stripe behind the second lateral 

 suture ; abdomen somewhat thicker ; basal ring on 3-8, very small 

 on 8, interrupted on 3 and sometimes on 4 ; a small lateral spot on 



