new Oenus of Odonata. 347 



from Mr. R. C. L. Perkins, who found the insect abundant 

 in the Hawaiian Islands, I am at length able to characterize 

 the genus. 



Genus Nesogonia. 



Frontal tubercle broad, slightly concave at the extremity ; 

 eyes very large, contiguous for a short space. Abdomen con- 

 siderably inflated at the base, the second and third segments 

 carinated, joints 4 to 6 of about equal lengtli, long and slender, 

 expanded at the tip and slightly also at the base, and more or 

 less contracted in the middle, the succeeding segments succes- 

 sively shorter. Wings long and moderately broad, shaped 

 much asin JEschna : fore wings with 11 antenodal cross-nervules 

 (exceptionally 10 or 12), the last only exceptionally continuous, 

 and 9 (rarely 8) postnodal cross-nervules; sectors of the arculus 

 stalked, nodal sector not waved, triangle rather broad, the 

 outer side very oblique, the inner side slightly waved ; tri- 

 angle traversed, followed by three rows of cells increasing ; no 

 supratriangular nervules ; subtriangular space consisting of 

 3 cells ; one cross-nervule in the lower basal cell: hind wings 

 broader than the fore wings; one (rarely two) cross-nervules 

 in the lower basal cell ; triangle free (exceptionally traversed 

 by one or two nervules) ; a supra-triangular nervule occa- 

 sionally present. On the hind wings the upperside of the 

 triangle strikes the outer side considerably below the level of 

 the lower sector of the arculus, instead of meeting the sector 

 at an acute angle as in most dragonflies. The same thing is 

 frequently observable in the fore wings too, but not inva- 

 riably. Head and thorax very hairy, and even the abdomen 

 visibly clothed with line short hairs. Legs long, thickly 

 clothed with rather long bristles and fine hairs. Claws 

 toothed considerably before the tip. 



Typical species : 



Nesogonia Blackburni. 



Lepthemis Blackburni, McLacblan, Ann. & Mag. Nat. Hist. (5) xii. 



p. 229 (1883), (6) x. p. 177 (1892). 

 SymjKtrum Blackburni, Karsch, Berl. ent. Zeitsclir. xxxiii. p. 373 



(lfc90). 

 Orthttrum Blackburni, Kirby, Cat. Neur. Odon. p. 36 (1890). 



Hah. Hawaiian Islands. 



I need not describe this species here, especially as Mr. Per- 

 kins is about to publish a fuller account of it than has yet 

 appeared, in his forthcoming work on tiie Insects of Hawaii. 



