KEY TO THE GENERA 
Adults 
1 Vein M 1-3 (upper sector of the arculus) springs from the slanting 
upper end of the arculus; triangle of the hind wing not divided 
by a cross-vein: no intercalary sectors running down to the 
wing margin in the two areas between veins M2, M3 and M4. 
Thorax black spotted with yellow.............. Tanypteryx. 
Vein M 1-8 springs from near the middle of a perpendicular 
arculus; triangle of the hind wing traversed by a cross-vein. 
There are well developed intercalary sectors in the marginal 
spaced between veins M2, M3, and M4; thorax yellow, striped 
10108 Cd ane ae eS MRC CaM AY IE GOP LS Tachopteryx. 
The nymph is known for but one of our species, Tachopteryx 
thoreyz; it is figured on page 60. 
The group is represented in our fauna by but two genera, each with 
a single species, one Eastern, one Western. It is much more abundantly 
represented in antipodean regions (Chile and Australia) and it wasa 
dominant group in past geological times, as evidenced by abundant 
fossils. 
1. TANYPTERYX Kennedy 
Includes the following species, and another, 7. preyerz, in Japan. 
1. Tanypteryx hageni Selys 
The Western Grayback 
Selys ’79, p. 68: Mtk. Cat. p. 74: Ndm. ’03, p. 739 (fig.): Kndy. ’17, p. 508. 
Length 55 mm. Expanse 74 mm. Nev. Wash. Calif. 
This is a large blackish species, rather conspicuously spotted with yellow. 
Face and occiput brown. Front of thorax black, with two upward-pointing 
yellow triangles just above the collar, and two smaller subtriangular spots just 
below the crest. Sides of thorax black with two pairs of rather large ovoid spots, 
the first pair behind the humeral suture, the second smaller pair behind. Legs 
black. Wings hyaline but with a slightly brownish tinge. Abdomen black with 
paired submedian dorsal yellowish spots on segments 2 to 7, slender and sinuous 
on 2, broader, but diminishing in size on 3 to 7. Segments 8 and 9 black. Ap- 
pendages black, with a pale spot on the sides of the superiors of the male at base. 
Nymph unknown. 
2. TACHOPTERYX Selys 
These are big, gray dragonflies of rather local distribution. The 
triangle of the fore wings is nearly equilateral, that of the hind wings 
54 
