AQUATIC INSECTS IN THE ADIRONDACKS 475 



&& Face blackish erroneous 



aaa Abdomen with lateral spots 



c Abdomen 65 mm or more in length (southern ) fasciatus 



cc Abdomen less than 60 mm in length 



d Spots single on sides of abdominal segments diastatops 



dd With large, separate, median and apical spots on sides of middle abdom- 

 inal segments maculatus 



As to the nymphs, few of them are known. Cabot^ has figured and 

 described as C. sayi (supposition) nymphs, which, later, Hagen^ has 

 referred to C. diastatops (supposition). These nymphs were from 

 Maine, Massachusetts, Maryland and Virginia. It is very doubtful 

 whether C. sayi occurs so far north as Massachusetts : owing to con- 

 fusion of species, published records of distribution of our species of 

 Cordulegaster need sifting. I have bred C. diastatops at Ithaca 

 and my nymphs agree with Hagen's description, and thus confirm his 

 supposition. In the above cited paper Dr Hagen also published brief 

 descriptive notes on two other Cordulegaster nymphs which he 

 referred by supposition to C. dorsalis (of the Pacific slope) and C. 

 obliquus (the latter one, a single imperfect specimen from Texas). 

 This is all that has been published concerning the nymphs of American 

 species of this genus. 



I describe below nymphs ofC, diastatops (raised) and C. 

 maculatus (supposition), and in order to avoid repetitions, I will give 

 herewith a general statement of the characters of nymphs of the genus : 

 they are all very much alike. 



Nymphs of this genus agree in the following points : the body is stout, 

 rough, hairy, cylindric, tapering beyond the middle of the abdomen to a 

 pointed apex, the longitudinal axis upcurved at both ends, the tips of the 

 eyes and the abdominal appendages being the highest points. The 

 antennae are seven-jointed, slender. The eyes cap the angular antero- 

 lateral prominence of the head and extend a pair of sharp points inter- 

 nally on the vertex from their hind angles. Hind angles of the head 

 rounded, the hind margin not obviously concave posteriorly. The 

 labium is very large, extending posteriorly between the bases of the mid- 

 dle legs, its dilated, spoon-shaped anterior end covering the face up to 

 the antennae, and meeting above a convex frontal prominence, whose 

 margin is fringed with sensory hairs. The mentum is triangularly 

 widened beyond the middle; its median lobe is produced in a median 

 tooth which is bifid on the median fine ; its lateral lobes are broad, tri- 

 angular, concave, and bear a row of short raptorial setae just within the 

 external margin, a stouter, but not longer movable hook at the end of 

 this row, and a series of coarse, irregular interlocking teeth on the distal 

 margin. 



1 Immature state of the Odonata. 1872. pt 1, p. 13, pi. 3, fig. 2. 



2 Monograph of the earlier stages of the Odonata, Am. ent. soc. Trans. 1S85. p. 290. 



