1915] Muttkowski: Studies in Tetragoneuria (Odonata) 53 
tanglement” the writer proposes to separate these arbitrarily 
into two groups, similar to those under T. cynosura. As in the 
case of the latter, it is “advisable to have each name cover as 
large a series as possible.” (I use my words of 1911. — R. A. M.) 
Hind wings with markings reaching the nodus and beyond 
semiaquea semiaquea Burmeister. 
Hind wings with markings not reaching the nodus, semiaquea calverti n.n. 
The writer generally deprecates the use of trinomial nomencla- 
ture. Nevertheless, he feels that there are certain problems of 
variation in systematics that are best served in this fashion. 
He feels therefore that a varietal name such as the above has no 
real systematic standing (i.e., on a morphological basis) but 
advocates its adoption on a basis of convenience. 
In view of the above notes the “key” as originally published 
is inapplicable for the present species. The following emenda- 
tions are offered: 
C. Temperate species, Carolinian to Transition (Ga. and Okl. 
to Maine and Minn.). Color expanse on hind wings increas- 
ing toward north, southernmost specimens being clear- 
winged, northernmost specimens with color beyond triangle 
(never to nodus). T-spot usually present, or indicated by 
metallic reflection in median frontal sulcus. Length of abdo- 
men rarely less than 28 mm. (28-32), hind wing 28-32 mm. 
Thoracic pile predominantly gray. 
D. Brown of hind wing reaching the base of the triangle, or 
less cynosura cynosura Say 
DD. Brown of hind wings reaching tip of triangle and filling 
it, or more cynosura simulans Muttkowski 
CC. Atlantic coast species, Florida to New Jersey. Color expanse 
on hind wings increasing toward north, southernmost speci- 
mens with color beyond triangle, or to nodus, northern- 
most specimens with color to nodus or beyond. T-spot 
absent. Length of abdomen rarely more than 27 mm. 
(23-27), hind wing 24-26 mm. Thoracic pile predominantly 
brown. 
D. Brown of hind wings not reaching nodus (to third and 
fourth antecubital). Georgia specimens 
semiaquea calverti n.n. 
DD. Brown of hind wings reaching nodus and beyond. North 
Carolina and New Jersey 
semiaquea semiaquea Burmeister.. 
