48 NEW YORK STATE MUSEUM 



' Imago. Length, 3.54.5 num.; setae, aibout 10 mm. additional; 

 expanse of wings, 8 num.; fore leg of male, 3.5 mm'. 



General color brown, marked with purplish or slat^i gray ; head 

 and thorax brown, earinae and margins of ocelli blackish. Wings 

 hyaline, with the usual purplish streak along the radius for two 

 thirds its length. Aibdomen pale ^^ellowish brown on base and 

 apex, the middle two thirds washed with gray; some elongate 

 blackish marks on the lateral margins of the 7th to 9th seg- 

 ments; setae white; antennae, femiora and forceps yellowish; 

 tibiae and tarsi, except the terminal joint, white. Venation of 

 the wing and the male forceps as shown in the aocompanying 

 figures ( figs. 8 and 9 ) . 



_, Fig. 9 Ventral view of 



Fig. 8 Venation of wing of ?Caenis allecta male abdominal append- 



sp. nov. ages of ?Caenis al- 



lecta sp. nov., imago. 



Nymph. Length, 2.5-4 mm.; setae, 1.5 J to 2 mm.; (^ mm. ad- 

 ditional. 



Color greenish brown, obscure on the head, with a transverse 

 broken and obscure line between the paired ocelli, antennae and 

 legs pale, a pair of brown submedian dots on the prothorax; ab- 

 dominal segments pale basally and on the sutures; gill covers 

 darker beyond the basal third ; segments 8-10 darker with a mid- 

 dorsal pale line on 8 and 9. Lateral spines on segments 3-9, flat 

 and ithin, best developed on the middle segments, becoming less 

 divergent poisteriorly and losing their lateral fringes of spinules. 

 Setae stout at base, rapidly tapering ; middle one distinctly longer 

 in female and shorter in male than the laterals, all with scanty 

 apical circlets of spinules on the segments. Legs scantily and 

 abdomen copiously beset witli short hair that is usually covered 

 with adherent silt. 



Aside from the not very satisfactory differences ot coloration, 

 this nymph differs f romi that of C. d, i m i n u t a in having the 

 sides of the prothorax parallel; in diminuta the prothorax is 

 widened anteriorly, and in having a greater part of the abdomen 

 covered by the opercular lamella; in this species that lamella 



