Vol. XXV] ENTOMOLOGICAL NEWS 445 



taken on both sides of Clifton, mocsta and scdnla are of wide 

 distribution, while apicalis is of more restricted and northerly 

 distribution. The truly remarkable Clifton list thus results 

 from the meeting here of species of wide distribution with 

 western and southwestern species. The distribution generally 

 of dragonflies seems to be, within certain limits, determined 

 by temperature and impassable barriers, subject only to the 

 formation, age and extinction of suitable water habitats. Con- 

 sider, for example, the distribution of Ischnnra kellicotti 

 known only from a few points in the extreme east, Indiana 

 and Oklahoma. 



In 1905 I collected 14 species of Aryia in Guatemala. Nine 

 species were taken at one point, Gualan, which, as in the case 

 of Clifton, seemed favorably located to receive elements from 

 two directions. Of the 9 species, I was taken at Gualan only ; 

 i was taken only in one direction ; 4 were taken only in the 

 other direction, and 3 were taken in both directions. 



17. Enallagma durum. 



Texas: Bay City, May 24, i $ ; Williams Lake, May 26. i 9 ; 

 Matagorda, May 25, i 9 . 

 IS. Enallagma civile. 



Texas: Brownsville, May 13 and 15, 5 $ , 2 9 ; i 9 in alcohol, 

 det. Calvert. Nov. 25, 1910 (C. A. Hart), 3 $ . one of them teneral; 

 Black Bayou, May 18, 19, 20, 21 and 23, 32 $ , i $ ; u $ , i 9 in 

 alcohol, det. Calvert; Clifton, May 30 and 31, 5 $ , i $ ; i $ in alcohol, 

 det. Calvert. 



Oklahoma : Wister, June 3, i $ , i 9 ; Henryetta, Aug. 7 and 30, 

 and Sept. 22 (Collins), 7 $ , I 9 . 



19. Enallagma traviatum. 



Oklahoma : Wister, June 3 and 4, 40 $ , 4 9 ; 2 $ in alcohol, det. 

 Calvert. Flying over the water at source of outlet of artificial lake 

 in numhers, pairing. 



20. Enallagma geminatum. 



Texas : Williams Lake, May 26, 3 $ , i 9 . 



Oklahoma: Wister, June 3, 2 $ , i 9,1 pair; i $ in alcohol, det. 

 Calvert. 



21. Enallagma divagans. 



Oklahoma: Wister, June 3, ~ $ , I 9 ; i $ in alcohol, det. Calvert. 



22. Enallagma basidens. 



Texas: Clifton, May 30 and 31, and June I, 12 $ . I pair; 2 $ in 

 alcohol, det. Calvert. 



