AQUATIC INSECTS IN THE ADIRONDACKS 483 



a low median ridge representing another on the loth segment, often little 



evident. The lateral spines, which occupy the sides of the eighth and 



ninth segments, are generally stout and flattened, and do not reach the 



level of the tips of the appendages. The loth abdominal segment is a 



little shorter than the ninth. 



Imagos 



a Length of abdomen generally less than 50 mm ; expanse of wiug less than 100 



mm; thoracic dorsum usually without yellow stripes illinoiensis 



aa Length of abdomen about 60 mm ; expanse of wing more than 110 mm; dor- 

 sum of the thorax with a jjair of short, yellow stripes taeniolata 



Nymphs 



a Lateral spines of abdomen directed posteriorly, hardly incurved; pyramidal 



horn on tbe front of the head acute at apex. ..il 1 inoiensis, supposition 



aa Lateral abdomiual spines strongly incurved at the tip ; pyramidal horn on 



the front of the head obtuse, hairy taeniolata, supposition 



Macromia illinoiensis Walsh 



1862 Macromia illinoiensis Walsh, Acad. nat. sci. Phil. Proc. p. 397 

 1893 Macromia illinoiensis Calvert, Am. ent. soc. Trans. 20: 251 (de- 

 scription) 

 1897 Macromia illinoiensis Van Duzee, N. Y. ent. soc. Jour. 5:89 

 (listed from Grand Island) 



1899 Macromia illinoiensis Kellicott, Odon. Ohio, p. 87 (description) 



1900 Macromia illinoiensis Williamson, Dragon flies Ind. p. 308 



(description) 

 1890 Macromia illinoiensis (nymph supposition) Cabot, Immature 

 state Odon. 3 : 16, pi. 1, fig. 2 and pi. 2, fig. 1 



A species which ranges from New Hampshire to Texas. Though taken 

 but once as yet within the state, it probably dwells in the borders of a 

 number of our larger bodies of water. I have not seen the imago at 

 large. I have seen a few of the nymphs referred to this species, and 

 may add a descriptive note covering some points unnoticed by Cabot. 



A nymph 26 mm long has a length of abdomen of 16 mm ; of hind 

 femur of 11 mm; a width of head of 7.5 mm, of abdomen of 11 mm. 



Head a little narrowed behind the very prominent eyes to the hind 

 angles, above each of which is a little superior tubercle ; labium greatly 

 widened anteriorly, and concave, forming an immense mask; lateral 

 setae six, with two little axial setae at the base of the lateral lobe within; 

 mental setae five each side, close together in row, with several more 

 minute, detached ones nearer the median line; teeth about five, large, 

 oblique, each armed with about four or five spinules. 



