THE CANADIAN ENTOMOLOGIST 169 



deeply concave within, the teeth on the distal margin obsolescent, 

 crenate, each with a single spinule; lateral setae 9 or 10; mental 

 setae 10- 13, the fourth or fifth from the outside longest, the inner 

 four smaller than the others. 



Abdomen broadest at seg. 6, scarcely narrowing on 7, slightly 

 on 8, more abruptly on 9; lateral spines on 8 one-half to three-fifths 

 as long as the segment, subparallel, those on 9 reaching about to 

 the tips of the inferior appendages, their inner margins straight 

 and parallel. Superior appendages somewhat less elongate than 

 in intacta, acuminate, about twice as long as the lateral appendages. 

 Dorsal hooks on segs. 3-8, larger on 3 and 4 than in intacta, less 

 erect and more curved, very slender; those on 5-7 of about the same 

 size as in intacta or somewhat larger and slightly more elevated, 

 the curve of the upper margins much stronger proximally, the 

 apices sharp and directed straight back, reaching about the middle 

 of the following segment; on 8 similar to those of the preceding 

 segments but less elevated, directed straight back. 



The coloration when well marked is so exactly similar to that 

 of intacta that it seems unneccessary to describe it. It is usually, 

 however, rather obscure, though the legs are always distinctly 

 banded. 



Measurements. — Length of body 15-16; abdomen 9-10.6; 

 hind wing 4-6-4.75; hind femur 4; width of abdomen 6-6.8; width 

 of head 4.7-4.8. 



EXILANATION OF PlATES I. AND II. 



Fig. 1. Nehalennia gracilis. — Lateral gill. 



Fig. 2. Nehalennia gracilis. — Hind margin of head. 



Fig. 3. Nehalennia Irene. — Hind margin of head. 



Fig. 4. Enallagrtia calverti. — Dorsal view of head. 



Fig. 5. Enallagma calverti. — Lateral gill.. 



Fig. 6. Enallagma hageni.— Dorsal view of head. 



Fig. 7. Enallagma signatum. — Dorsal view of head. 



Fig. 8. Enallagma signatum. — Lateral gill. 



Fig. 9. Enallagma polliitum. — Dorsal view of head 



Fig. 10. Enallagma pollutum. — Lateral gill. 



Fig. 11. Boyeria grafiana. — Labium. 



