NEDKOPTERA ODONATA OPUIOGOMPHUB SEVERUS. 1)17 



with a broad, black band in the middle, following the sinus above, and 

 united with a complete black band on the humeral suture. Mesothoracic 

 crest from the bifurcation to the prothorax yellow ; a large, ovoid, black 

 spot each side of the dorsum, not confluent with the bands ; a black band 

 on the second lateral suture, nearly united by a superior line at the base of 

 the wings with a lateral band ; an inferior, incomplete, black band on the 

 first suture, ending at the stigma, Abdomen cylindrical, enlarged at the 

 base, and on the seventh to ninth segments greenish-yellow ; all the seg- 

 ments each side on the apical half with a large, blackish band ; the bands 

 are interiorly dilated at the tip and converging (diverging on the first seg- 

 ment) ; venter black on segments 3 to 6, orange on the following. In the 

 Yellowstone male, the bands are broader and confluent on the tip; the yel- 

 low part between the bands forming a basal, hastiform spot ; appendages 

 yellow, the superiors about as long as the last segment, short, parallel, stout, 

 trigonal, exteriorly rounded, subincurved, pointed on tip, which is bent out- 

 ward, beneath somewhat thickened before tip, with numerous small, black 

 spines ; inferior appendage a little shorter, triangular, bifid to the base, con- 

 tiguous, the basal half forming an obtuse elevation, the apex recurved with 

 a small, black, superior tooth; genital parts in the second segment with the 

 first hamule forming a lobe interiorly hollowed ; the tip with a semicircular 

 excision, the hind angle of the tip prolonged in a strongly bent, slender, 

 black hook ; second hamule longer, the tip suddenly nan-owed, a little 

 recurved, blackish, cut straight ; penis with an inferior tooth on second 

 joint, the last one with two long spines ; sheath of the penis hollowed out, 

 four-lobed, the two inner lobes cylindrical, divergent, the outer ones large, 

 flat, semicircular ; earlets yellow, large, rounded, on the hand band a series 

 of small, black teeth. The female has the occiput exactly similar to the 

 male, without any posterior teeth; appendages yellow, short, pointed; vul- 

 var lobe triangular, a little shorter than the segment, bifid to the base, con- 

 tiguous, indented short before the sharply pointed black tip, which is bent 

 outward ; feet yellow ; femora an apical superior black band, beginning on 

 the knee, divided anteriorly, beneath with numerous, very short, black 

 spines ; tibia? black beneath, and interiorly or on both sides with a black 

 line and long, black spines ; tarsi black, all, or only the basal joint, yellow 



