462 PROCEEDINGS OF THE ACADEMY OF [Oct., 



area between the latter and the Isthmus of Nicaragua and only one 

 (Thaumatoneura) to the Costa Rican-Panaman section. 



The predominant Calopterygine genus is Hetcerina with 17 species out 

 of 23 for the subfamily. Several species (H. americana, tricolor, 

 titia, macropus, capitalis) show a marked tendency to reduction in size 

 of the pterostigma in some of the western portions of their ranges, 

 but the geographical areas in which this reduction is strongly marked 

 for one species (e.g., macropus in Guatemala) are not necessarily 

 those in which it is displayed by another {e.g., americana). Amphip- 

 teryx is interesting as presenting some features intermediate between 

 those of this subfamily and the Agrioninse. Only one Old World 

 genus (Calopteryx) is represented and its existence here rests on a 

 single specimen. 



Lestince. Six of the 7 species belong to the cosmopolitan Lestes. 



AgrionincB. Of 24 genera, 3 only {Argia, EnaUagma, Ischnura) 

 have been recorded from the Old World. Five of the 7 endemic 

 Odonate genera belong here. Of the 112 species, 48 belong to Argia; 

 next follow Protoneura with 7 species and Telebasis with 6. Six 

 species (of 3 genera) are of the exclusively Neotropical Pseudostig- 

 matina, including some of the linearly largest known Odonata of the 

 world. 



Gomphince. None of the genera are extra-American. Erpetogom- 

 phus is the predominant genus of the subfamily in the northern part 

 of our district, Epigomphus in the southern. 



Cordulegasterince. The single genus of our area, Cordulegastcr, 

 is Holarctic. 



Mshnince. Three {Anax, JEshna, Gynacantha) of the six genera 

 are also found in the Old World, but none of the species extends thither. 

 One of the seven endemic genera belongs here (OplonascJma) . /Eshna 

 has the largest number of species. 



Cordulince. The single record for this subfamily, from near the 

 northern limit of our district, is of the Holarctic and Pala^otropical 

 Macromia. 



Libellulince. Of 28 genera, one (Pseudoleon) is endemic, five (Libcl- 

 Ivla, Tholymis, Tramea, Pantala, Sympetrum) are regarded as also 

 occurring in the Old World. The only Odonate species common to 

 our area and to the Old World — Pantala flavescens (and Sympetrum 

 corruptum?) — are of this subfamily. Predominant genera are Libel- 

 lula, Micrathyria, Orthemis, Erythrodiplax, Brechmorhoga , Tramea, 

 Perithemis and Erythemis. 



