AQUATIC INSECTS IN THE ADIRONDACKS 



537 



1867 Libellula trimaculata Packard, Am. nat. 1 : 310, pi. 9, fig. 1 

 1861 PI a the mis trimaculata Hagen, Synopsis Neur. JST. Am. p. 149 

 1873 Libellula trimaculata Riley, Ins. Mo. 5tb rep't, p. 14 (This article 

 contains a woodcut of this species which has been most extensively 

 copied in this country.) 

 1893 Plat hemi s trimaculata Calvert, Am. ent. soc. Trans. 20:259 

 1895-97 Platherais trimaculata Calvert, N. Y. ent. soc. Jour. 3 ; 47 

 and 5: 94 (listed from New York, Dobbs Ferry, Ithaca, Schoharie, 

 Albany and Buffalo) 



1898 Li bell ul a trimaculata Needham, Outdoor studies, p. 57 and 65, 



fig. 56 and QQ 



1899 Plathemis trimaculata Kellicott, Odon. Ohio, p. 102 (description) 



1900 Plathemis lydia Williamson, Dragon flies Ind. p. 333 (description) 

 This is another well known, widely distributed and generally common 



species, which inhabits ponds and ditches generally. I present herewith 

 (fig. 32) a figure of its nymph, which I have pre- 

 viously pubhshed in Outdoor studies. It differs from 

 Libellula and Ladona in having the head 

 widest behind the eyes, and from Libellula in 

 having the front margin of the median lobe of the 

 labium crenulate. 



Nymph. Total length 24 mm ; abdomen 14 mm ; 

 hind femur 4.5 mm; width of head 4.5 mm, of abdo- 

 men 5.5 mm. 



Body elongate, rather smooth, and more free from 

 dirt than most Libellulas, generally showing two 

 bands of blackish brown extending from beneath the 

 tips of the wing cases to the bases of the lateral ap- 

 pendages. Head not widened behind the eyes, but 

 with sides parallel; median lobe of labium promi- nymph of piathemis 

 nent, but with no middle tooth on its fore margin ; ^^^'^^ ^''"• 

 lateral setae 10; mental setae eight; of which the five outer ones are 

 longer; abdomen triquetral, with moderate lateral spines on segments 

 8 and 9, and with rudimentary dorsal hooks on segments 3-5, highest on 

 the fourth segment, absent from the hinder segments; lateral appendages 

 about half as long as the equal superior and inferiors. 



Fig. 32 Doi-sal view of 



TRAMEA 



But two species of this large genus seem to belong to the New York 

 fauna. These are insects of superb aerial powers, representing, together 

 with the next genus, the extreme of specialization in wing development, 

 at least for the subfamily. Our two species may be recognized, even 

 while in flight, by the broad, basal colored band on the hind wings. The 

 nymphs agree in having the body smooth, depressed, unusually clean and 

 marked with a pattern of brownish on a ground of clear transparent green; 



