50 PAPERS ON ZOOLOGY OF MICHIGAN. 



AA. Anal triangle of the hind ving of the male usually consisting of two cells; genital valve 

 ot the female not strongly elevated at the apex. 



B . A black line on the fronto-nasal suture; hamular processes short and broad. 



A. interrupta 



BB . No blaciv- liiie on the fronto-nasal suture. 



A. canidensi') 



Nymphs. 



A. Mentum of the labium distinctly more than half as broad at the base as at the apex. 



B. Lateral labial lobes squarely truncate, the outer apical angle scarcely rounded. 



A. interrupta 



BB . Lateral labial lobes not truncate, but curving to a prominent, apical hook. 



A canadensis 



A A. Mentum of the labiimi not, or scarcely, half as broad at the base as at the apex. 



A. constricia 



Aeshna constricta Say. — Nymphs of this species were taken in Bessey 

 Creek and Bryant's Bog. Prof. Frank Smith also collected several 

 specimens in Indian River, the outlet, at the extreme southern end of 

 Burt Lake about nine miles from my Burt Lake station. 



Aeshna interrupta Walker. — -This species was reported from Douglas 

 Lake in 1910, one specimen being taken on August 18. 



Aeshna canadensis Walker. — This species was reported common to 

 the region during the summer of 1910. Neither nymphs or adults were 

 taken during the summer of 1910. 



GENUS AX AX LEACH. 



Anan Junius (Drury). PI. IX, Fig. E.; PI. X, Figs. E, F. — ^Both 

 adults and nymphs of this dragonfly were common all summer. Nymphs 

 were taken from the submerged vegetation at Smith's Bog, Bryant's 

 Bog and the beach pool near North Fishtail Bay, usually in water 

 which was relatively quiet. The adults of the species were taken in 

 various situations about the water as well as in the aspens near the lake. 



GENUS DROMOGOMPHUS SELYS. 



Dromogomphus spinosiis Selys. — One specimen of this species, 

 undergoing exuviation, was taken on the dock near camp. 



FAMILY LIBELLULIDAE. 



KEY TO THE SUBFAMILIES OF LIBELLULIDAE. 



Imagos. 



A. Sectors of the arculus distinctly separated. 



Subfamily Cordulinae 



AA. Sectors of the arculus in close proximity or completely fused for a short distance from the 

 arcuLus. 



Subfamily Libellulinae 



