No. 39] ODONATA OF CONNECTICUT: GOMPHIDAE 139 



The nymphs of this ^enus are found in small swift-flowing 

 brooks, usually in shady situations. Adults are apparently rarer 

 than the nymphs and it is probable that the species have the 

 explosive dispersal habit of their near relatives. 



Lanthus albistylus Hagen 



Bulletin de rAcademie royale . . . de Belgique, 46 : 460 : 1878. 



Nymph (PL iii, Fig. 9). — Color dark brown. 



Head : median lobe of labium gradually contracted behind the 

 middle; apical tooth of the proximal segment of the labial palpi 

 not produced and hardly distinguishable from the teeth of the 

 mesal margin (PI. v, Fig. 5). Third segments of the antennae 

 greatly enlarged, spoon-like, and about three times the width of 

 the proximal segments, the fourth segment minute and incon- 

 spicuous. 



Thorax : legs with tips of femora pale, the wing-cases extend- 

 ing to the middle of the fourth abdominal segment in full-grown 

 specimens. 



Abdomen : flattened, with only rudimentary lateral spines on 

 segments 8 and 9 ; width of the ninth abdominal segment more 

 than twice as great at front margin as at the hind ; no dorsal 

 spines or prominences. 



Measurements: total length, 19 mm.; length of abdomen, 11 

 mm. ; length of hind femora, 2 mm. ; length of median lobe of 

 labium, 2 mm. long by 1.8 mm. wide. 



Described from a male exuviae, the adult emerging June 3, 

 1922; collected at Orange, Conn. 



Adult, male. — Color yellow and black. 



Plead : yellow and black, the following black : ventral and dorsal 

 margins of the labrum, and a mark on the meson half the length 

 of the sclerite ; furrows between ante- and postclypeus ; all of 

 front including ocellar area, except an elongate transverse area in 

 front of the antennae (2 by .5 mm.) ; and all of vertex except 

 a small spot on caudal surface between the compound eyes and 

 another caudad of the ocelli on the vertex, the latter sometimes 

 absent ; all of occiput and postgenae dark ; compound eyes sep- 

 arated by .9 mm., measured on the transverse epicranial suture. 



Thorax : pronotum black with two small mesal spots, a lateral 

 spot on each side and portions of the cephalic margin green ; pro- 

 pleura pale; meso- and metathorax mostly yellow ; anepisterna of 

 mesothorax dark brown, with two yellow stripes, and a yellow 

 collar, the dorsal stripe 1.5 mm. long by .4 mm. wide, the lateral 

 stripe 2 by .3 mm., and contracted in the middle, sometimes inter- 

 rupted ; mesopleural suture sometimes with a pale line ; ventral 

 half of the katepisterna yellowish green; mesepimera entirely 

 green except the narrow brown margins ; metapleura green ; 

 venter pale (Fig. 22, No. 18) ; legs black, with coxae and tro- 



