546 



PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 52. 





Figs. 224-226.— Ophiogomphus bison, nymph. 224. Mentum. 225. Teeth and setae on MmDLE lobe 



of mentum. 226. segments 6-10. 

 Figs. 227-229.— Ophiogomphus moreisoni. 

 Figs. 230-232.— Ophiogomphus seveeus. 

 Figs. 233-235.— Ophiogomphus moeeisoni nevadensis. 

 F>GS. 236-238.— Ophiogomphus occidentis. 



