526 



rows of setae ; metathoracic wing-cases extending caudad to the middle 

 of the fourth abdominal segment. 



Abdomen long and slender, uniform buff, the cuticle provided 

 with minute setae; segments 3-10 with dorsal transverse rows of setae 

 at the caudal margins and segments 3-y with similar ventral rows, the 

 setae grouped somewhat conspicuously on the meson ; lateral keels 

 strongly developed, setose, the keel of the first segment with a number 

 of heavy setae, usually three, that of the second with a row of eight or 

 nine, and keels of the third to the eighth segments with a row of ten or 

 twelve, and with groups of two or three at the apices ; ninth segment 

 with a lateral row of setae in line with the lateral keels ; gills (Fig. 80) 

 very long, somewhat spatulate, the points mostly blunt, and the dorsal 

 marginal row of setae of the median gill extending much beyond the 

 middle ; three narrow transverse bands sometimes occur just beyond 

 the middle ; they are placed closely together as a rule, but the bands 

 may be reduced to one or may be wanting. 



Measurements 



Length 15 mm. 



Length of abdomen 9 mm. 



Length of gills 7 mm. 



Width of gills 1.8 mm. 



Length of median lobe 2.3 mm. 



Width of median lobe 8-1.6 mm. 



Described from three specimens in the collection of the State 

 Laboratory of Natural History, collected at Havana, 111., June 30, 

 1897. 



The nymph has not been reared, but the specimens were deter- 

 mined from a description given by Walker. 



Adult; Male. — Color, blue and black. 



Head blue and black, buff below; labium buff, the median lobe 

 subtriangular, the apical cleft narrow; distal segment of the labial palpi 

 pale ; postclypeus black except the lateral margins, anteclypeus, labrum, 

 mandibles, their trochantins, genae, and the transverse area above the 

 clypeus blue; lateral ocelli with a small blue spot cephalad of each, the 

 remainder of the front and vertex black ; pale line caudad of the ocellar 

 area distinct, the ends narrowly separated from the large blue, cunei- 

 form postocular spots; occiput pale except a transverse black line bor- 

 dering the postocular spots. 



Thorax blue and black ; pronotum mostly black, with a large blue 

 spot on each median lobe, the caudal margin of the caudal lobe and 



