592 GEOLOGICAL SURVEY OF THE TEEKITOEIES, 



from Yellowstone, preserved dry, shows the following pattern) : dorsum 

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

 united with a complete black band on the humeral suture. Mesotho- 

 racic 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 the humeral band ; an inferior, incom- 

 l)lete 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 segments 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 segment) ; 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 yellow part between the bands 

 forming a basal liastiform spot; appendages yellow, the superiors 

 about as long as the last segment, short, parallel, stout, trigonal, exte- 

 riorly rounded, subincurved, jiointed on tip, which is bent outward^ 

 beneath somewhat thickened before tip, with numerous small black 

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

 contiguous, 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 Ibnger, the tip suddenly nar- 

 rowed, 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 hind band a series of small, black teeth. The female has the occi- 

 put exactly similar to the male, without any posterior teeth ; append- 

 ages yellow, short, pointed ; vulvar lobe triangular, a little shorter than 

 the segment, bifid to the base, contiguous, 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 anteri- 

 orly ; beneath with numerous very short black spines ; tibioe black be- 

 neath and interiorly or on both sides with a black line and long black 

 spines ; tarsi black, all or only the basal joint yellow above ; wings hya- 

 line, veins black ; the costa and some transversals yellow ; pterostigma 

 oblong, a little dilated in the middle, yellowish, darker in the middle, 

 covering nearly three areolets ; 11-12 antecubitals, 7-10 postcubitals ; 

 2 discoidal areolets ; membranula whitish. 



Length of the body, 51 millimeters ; alar exi)ansion, 61-68 millime- 

 ters ; pterostigma, 2^ millimeters. 



Habitat. — Colorado (Mr. James Eidings) ; foot-hills and plains of Col- 

 orado. End of September (Lieutenant Carpenter); Fort Garland, Col- 

 orado, June 27, South Montana and Yellowstone (Mr. C. Thomas). This 

 is the species given in mj last report (j). 726) doubtfully as G. colubrinus. 

 This interesting species is very near 0. colubrinus in the appendages and 

 genital parts of the male, but different in the pattern of color on the 

 head and abdomen and the structure of the occiput in both sexes. 0. 

 colubrinus is a species rarely to be found in collections ; even the female 

 is not yet described. To prevent doubts about the rights of 0. severus, 

 I give here a description of the female of 0. colubrinus. I do not pos- 

 sess the male, and my manuscript description of it is still in Europe. 



0. colubrinus, Hagen, Synop., 101, 7. 

 FemaU. — Greenish-yellow, marked with black ; labium luteous, the 



