228 PROCEEDINGS OF THE ACADEMY OF [May, 



9. AI2 separates from Mi at five-thirteenths ( = .38) of the distance 

 from nodus to stigma. (In No. 5, however, the distance is 

 only .28, in No. I 8423 B. M. it is .26.) 



10. Between M2 and Rs is one row of cells increasing to two and then 



three rows, and so continuing to the margin. 



11. Rs separates from Mi + 2 at the subnodus. (Nos. 3, 4, 5, and 



B. M. I 15,049 show this clearly; B. M. I 8423 apparently 

 agrees with them; No. 1 has the point of separation slightly 

 proximal to the subnodus, while in No. 2 this part is indis- 

 tinguishable.) 



12. Between Rs and Ms is one row" of cells, increasing to two and then 



to three rows of cells. 



13. Arculus slightly proximal to the second antenodal.- 



14. M3 separating from M1+2 at six-tenths' to three-fourths' way 



from arculus to subnodus. 



15. Between Ms and M4 are (a) at least two cross-veins proximal to 



the level of the subnodus,^ and (6) at the wing-margin are 4-5 

 rows of cells. 



16. Quadrilateral with («) its proximal and distal sides strongly 



diverging caudad and (6) its distal side more than one-and 

 one-half times as long as its proximal side. 



17. Between Mi and Cui are (a) seven antenodal cells {sensu Selysii) 



and (6) at the wing-margin four to five rows of cells. 



18. Cubito-anal cross-veins one, which is situated between the 



levels of the first and second antenodals. 



19. Between Cui and Cu2 at the wdng-margin are about two rows 



of cells (three rows in B. M. No. I 15,049). 



20. Area posterior to Cu2 without distinct branches, but with three 



to four rows of cells. 



21. Anal vein separating from the hind wing-margin (a) proximad 



to the level of the arculus and (6) proximad to the level of the 

 cubito-anal cross-vein. 



22. Anal cross-veins, proximal to the level of the distal end of the 



quadrilateral, one. 



Compared with Professor Cockerell's original description of 

 Phenacolestes mirandus (1908a, p. 61), the present material shows the 

 following differences : 



Antenodal cross-veins^ four in some specimens instead of five. 



Basal space {i.e., cell M1-4) 4 mm. long, instead of nearly 5 mm. 



2 For B. M. No. I 8423 I have even noted, "Arculus very slightly more distal 

 than midway between the two normal antenodals." 



» The second, or distal, of these is actually at the subnodus in the two British 

 Museum specimens. 



4 Prof. Cockerell speaks of antenodal and postnodal sectors meaning these 

 cross-veins. This word is not in accordance with the usage of other authors on 

 the Odonata. R3 in the same description should be Rs. 



