Il6 CONNECTICUT GEOL. AND NAT. HIST. SURVEY [Bull. 



Adults 



1. Labial palpi meeting in a line on the meson; antenodal cross-veins 



of the first and second series usually"^ corresponding or in line 



with one another LIBELLULIDAE, p. 198 



Labial palpi not meeting in a line on the meson ; antenodal cross- 

 veins of the first and second series not corresponding or in line 

 with one another except the first and usually one other, which 

 varies in position 2 



2. Compound eyes contiguous for a considerable distance above . . . 



AESHNIDAE, p. 169 

 Compound eyes touching at a single point only, or widely separated 3 



3. Compound eyes subcontiguous or contiguous at a single point ; 



some of the spines of the middle and hind tibiae of the male 

 replaced by small tubercles, each with a small seta alongside ; 

 stigma without an oblique or with a very slightly oblique cross- 

 vein caudad of its proximal end and not more oblique than other 

 cross-veins in that vicinity . . . .CORDULEGASTERIDAE, p. 118 

 Compound eyes widely separated, the distance between them being 

 as much or more than half the distance between the antennae; 

 spines of the second and third tibiae of the male not replaced by 

 small tubercles 4 



4. Labium (mentum) bifid; female with a long ovipositor (Fig. 24, 



No. i) PETALURIDAE, p. 116 



Labium entire ; female without a long ovipositor, the latter greatly 

 reduced and not extending to the caudal margin of segment g 



GOMPHIDAE, p. 124 



Family PETALURIDAE 



Adults and Nymphs 



This family is represented in North America by a single genus 

 Tachopteryx, including only two species in the United States. 

 The adults have a bifid labium and the nymphs are characterized 

 by the possession of antennae with subequal segments, these seg- 

 ments being wider than long. 



Genus Tachopteryx Selys 



The nymphs are provided with thick stout legs. The labium is 

 broad and has a shallow cleft at tip of median lobe, the distal 

 margin of which is provided with very small teeth. 



Adults of this genus have a very oblique cross-vein supporting 

 the proximal end of the long narrow stigma. 



Very little is known of the habits of the only species of this 

 genus in the eastern United States. It has usually been observed 

 resting on trees or fences near streams or marshy areas. 



Tachopteryx thoreyi Hagen 



Monographie des Gomphines, Z72 '• 1858. 



Nymph. — The following description is taken from Williamson, 

 Ent. News, 12: 1-3: 1901 : 



"In Tratnea (Libellulidae) these veins frequently do not correspond (PI. xv, Fig. 2). 



