no. 2089. NOTES ON NEOTROPICAL DRAGON FLIES— WILLIAMSON \ 



611 



Comparison of characters of Palaemnema paulina and P. nathalia — Continued. 





paulina. 



nathalia. 



Cui ending beyond 

 origin of M Ja in 

 front wing (i. e., 

 number of mar- 

 ginal cells pos- 

 terior to Cm api- 

 cal to origin of 

 Mu). 



Male, 2-9 cells (1 wing has 2; 1, 3; 1, 3.5; 1, 4; 

 2, 5; 1. 5.5; 1, 6; 5, 7; 1, 7.5; 4, 8; 2, 9), aver- 

 age oi 20 wings, 6.32; female, 3-6 (1 wing 

 has 3; 1, 3.5; 2, 6). 



Male, 5 and 7; female, 4.5 and 6.5. 



Same of hind wing. 



Male, 7-13 cells (2 wings have 7; 1, 7.5; 1, 8; 

 1, 8.5; 3, 9; 1, 9.5; 2, 10; 3, 11; 1, 11.5; 4, 12; 

 1, 13), average of 20 wings, 10; female, 

 7.5-10 (1 wing has 7.5; 1, 8; 1, 9; 1, 10). 



Male, 11 and 13; female, 9. 



Number of cells 

 surmounted by 

 stigma, front 

 wing. 



Male, 2-3.5 (5 wings 2; 9, 2.5; 5, 3; 1, 3.5), 

 average of 20 wings, 2.55; female, 2-3 (1 

 wing 2; 2, 2.5; 1, 3). 



Male and female, 2. 



Same of hind wing. . 



Male, 2-3 (1 wing 2; 9, 2.5; 10, 3), average of 

 20 wings, 2.725; female, 2. 



Male, 2; female, 1.5 and 2. 



In two front wings and one hind wing of the 10 males of paulina 

 carefully studied the cubito-anal cross-vein is midway or slightly 

 closer to the first antenodal; in all the others it is closer to the second 

 antenodal. The unusual condition is due to the more apical position 

 of the first antenodal in these cases, the position of the second ante- 

 nodal being relatively fixed by its relation to the arculus (some slight 

 variation, as the second antenodal is at or slightly proximal to the 

 arculus). When the second antenodal is proximal to the arculus 

 the result is that the cubito-anal cross-vein is placed relatively nearer 

 the second antenodal. To sum up, variation in this character — the 

 cubito-anal cross-vein nearer the first or second antenodal — might 

 arise from 3 widely different causes: (1) The subquadrangle may be 

 lengthened basally, and the cubito-anal cross-vein may really be placed 

 basally with reference to other wing structures; or (2) the first 

 antenodal may be moved apically or basally, shortening or lengthen- 

 ing the distance between the antenodals; or (3) the second antenodal 

 may be moved apically or basally, lengthening or shortening the 

 distance between the antenodals. Of course one or all of these 

 conditions might be present in the same wing. 



All the specimens of Palaemnema in my collection have been 

 examined as to the number of antenodals. Variation is shown in 

 this character in 3 front wings and 1 hind wing of males of paulina, 

 in each of which there are 3 antenodals in the first series. Two of 

 the front wings belong to the same individual; the other 2 cases are 

 in two individuals. In the case of the 3 front wings the added ante- 

 nodal is basal to the normal antenodals; in the hind whig it is placed 

 between the 2 normal antenodals. The variation differs therefore 



