234 



THE CANADUN ENTOMOLOGIST. 



in the male, and the length of the vulvar lamina in the female. These 

 have proved unsatisfactory, especially for the males (of which more are 

 known), yet without destroying faith in the validity of the two genera as 

 natural groups. I wish to point out that there is a venational character, 

 applicable to both sexes, which seems to segregate these two genera 

 sharply. It is the anal loop (see figs. 31 and 33). In Ophiogomphus 

 (fig. 31) the first and second branches of the anal vein (i and 2) are 

 approximated near their origin to enclose, together with a cross vein 

 connecting them, a distinct anal loop (a) of two to four (normally of 



I I 



Fig. 31.— Ophiogomphus. 



Fig. 3?.— Onvchogomphi's. 



Fig. 33,— Hfrpetogompkis. 



three) cells. In Herpetogomphus (fig. t,!,) these veins are not so approxi- 

 mated, and no such semicircular enclosure is formed, but two ordinary 

 cells lie between the veins at their origin. 



The genus Ophiogomphus includes, besides four European and 

 Asiatic species, the following thirteen nominal species found in the United 

 States, named in the order of their discovery : 



1. O. colubrinus, Selys. — Maine and northward. ^ and $ known. 



2. O. rupinsulensis, Walsh.' — Eastern U. S. S ^-'^d $ known. 



3. O. Mainensis, Packard. — Northeastern U. S. c? ? and 9 known. 



4. O. bison, Selys. — Nevada. 9 known. 



5. O. severus, Hagen. — Colo. (J and ? known. 



6. O. montanus, Selys.— Mont. ^ known. 



7. O. Morrisoni, Selys. — Nev. c^ and $ known. 



8. O. occidentis, Hagen.* — Wash. ^ and 9 known. 



9. O. Carolinus, Hagen.* — N. Car., Ky.? ^ and $ known. 

 ID. O. aspersus, Morse. — S ^i^d $ known. 



*Imago undescribed. 



