NORTH AMKRIOAN ODONATA. 



267 



Subfamily GOMPHIN^ (7 species). 

 24. Gomphus abbreviatus* 



Subfamily AESCHNIN^ (6 species). 



31. Episeschna heros 



32. Ponscolombia vinosa-j- 



33. Gompbseschna furcillata var. 



antilope* 



34. Aeschna juncea var. verticalis 



35. " constricts 



36. Anax Junius 



Subfam. CORDULIN^ (6 species). 



37. Didymops transversa* 



38. Macromia tseniolata* 



39. " illinoensis* 



40. Epicordulia princeps* 



41. Tetragoneuria cynosura 



42. Somatochlora lepida* 



Subfam. LIBELLULIN^ (24 .species). 



43. Pantala flavescens* 



44. " hymensea* 



45. Tra^mea Carolina* 



46. " lacerata* 



47. Libellula basalis 



48. " cyanea 



49. " axillena form vibrans* 



50. " exusta 



51. " quadrimaculata 



52. " semifasciata 



53. " pulchella 



54. Plathemis trimaculata 



55. Micrathyria berenice* 



56. Nannothemis bella 



57. Celithemis elisa 



58. " eponina* 



59. Leucorhinia intacta 



60. Diplax rubicundula 



61. " semicincta 



62. ' ' vicina 



63. ' ' corrupta* 



64. Perithemis domitia 



65 Mesothemis simplicicoUis 

 66. PacLydiplax longipennis 



Of those species marked with an asterisk (*), only five individuals 

 or less, are known from within the twenty-mile radius. 



SEASONAL DISTRIBUTION (Imagos). 



The species of Odonata which appear first in the year around 

 Philadelphia are Anax Junius, Ischnura verticalis and Nehalennia 

 posita. The earliest date recorded for them is May 1, but they are 

 probably to be found still earlier. From the data contained in 

 Part II, it appears that the number of species to be found on any 

 one day increases from 3 to 14 during May, from 14 to 32 during 

 June, decreases from 32 to 23 during July, from 22 to 21 during 



t On Sept. 18, 1893, the writer took one % and saw another of vmosa by a 

 brook in Springfield Twp., Del. Co., Pa. 



TEANS. AM. ENT. SOC. XX. 



SEPTEMBER, 1893. 



