oT-1 



THE AMERICAN NATURALIST [Vol. XLII 



standing between Columbia and Aphredoderus in the 

 serial arrangement. 



Another waning group of fishes (with a single living 

 species) found at Florissant is Amia, the bowflns. The 

 accompanying figure shows a tail of this genus we found ; 

 much hunting failed to discover the rest of the specimen. 



A Primitive Dragonfly 

 The Zygopterous dragonflies are divided into families 

 known as Calopterygidac and Agrionida?. The Calop- 

 terygidae are further divided into subfamilies, separable 



by the character of the costal region toward the base of 

 the wing. In the Calopterygina?, this area, before the 

 nodus, is crossed by four or more veins, called antenodals ; 

 in the other subfamily, the Lestime, these have been re- 

 duced to two. In the family Agrionidae, which is very 

 abundant in the modern fauna, the reduction to two 

 antenodals is practically universal. There is, however, 

 an extinct subfamily, which 1 have called Dysagrionime, 

 in which this reduction has not gone so far, and four or 

 more antenodals remain. Of this group we know two 

 genera, Dysagrion Kcudd, from the Green River beds, and 

 Phenacolestes Ckll. from Florissant. The latter genus, 



