436 NEW YORK STATE MUSEUM 



d Wiug cases strongly divergent on the two sides; lateral lobe of labium blunt 



at apex Ophiogomphus 



hh Wing cases laid closely parallel along the back; lateral lobe of labium 

 endiug in a sharp, incurved hook 

 c Abdomen very thin and flat, circular in outline as seen from above; third 



segment of antenna flat and subcircular Hagenius 



cc Abdomen less depressed, ovate to lanceolate in outline, at least twice as 

 long as wide 

 d Third joint of antenna very flat, thin, and in outline circular or 



broadly oval Lanthus 



dd Third joint of antenna elongate, linear, little flattened 



e Dorsum of the ninth abdominal segment rounded, or with a low, obtuse, 



median longitudinal ridge , G o m p hu s, sens. lat. 



ee Niuth abdominal segment with a sharp middorsal ridge, endiug in a 

 straight apical spine Dromogomphus 



The genus Progomphus has not yet been found in New York 

 state, but it will probably be eventually. It ranges from Massachusetts 

 southward and westward across the continent, a single P. obscurus 

 Selys, having been taken in the whole northeastern United States. 



OPHIOGOMPHUS 



Four species of this genus are known from New York state. A fifth, 

 O. mainensis Packard is in our lists, but erroneously, I believe. 

 The specimens on which the record is based are in the Lintner collec- 

 tion and in the museum of comparative zoology. I have examined 

 them all, and they certainly belong to O. carolus Ndm., which I 

 believe to be a distinct species. The error seems to have come in the 

 associating of males of O. car o 1 us from New York with the female 

 type of O. m a i n e n s i s. Our four species may be separated as 

 follows. 



KEY TO THE NEW YORK SPECIES 



Imagos 



a Sides of the middle and hind femora yellow ; the inferior abdominal 

 appendage of the male narrower than the superiors, not visible from 

 above 

 & No black line on the third lateral suture (fig. 10) of the thorax; abdominal 

 segments mostly yellowish or brownish, marked with black apically 



rup insulensis 

 6Z> Third lateral suture of the thorax black, middle abdominal segments black on 



the dorsal side aspersus 



aa Sides of the middle and hind tarsi black ; the inferior, abdominal appendage 



of the male wider than the superiors, its lateral angles visible from above 



c Forks of the inferior abdominal appendage of the male apparently again 



forked, the apex of each bearing two strong, upcurved teeth separated by 



a deep rounded notch „ johannus 



