1908.] NATURAL SCIENCES OF PHILADELPHIA. 489 



in some cases restricted apparently to a single locality (Hetasrina 

 rudis), in others having a wide range of elevation, as from the sea- 

 coast to the central plateau (Anomalagrion hastatum, Ceratura capreola). 

 Where the same species of Ischnura has been found at quite different 

 altitudes, a slight increase in body size and in the number of post- 

 cubitals has heen detected in specimens from the higher stations. ^^ 



In concluding this discussion of the relations of the Odonata to vari- 

 ous factors of their environment, lists of the forms recorded from a 

 few localities of decidedly different physical character are appended. 

 See also the lists given for the Distrito Federal, Cuernavaca and San 

 Jose on page 481. 



Guzman, Chihuahua (desert of Northern Mexican plateau, mean annual 

 temperature probably near 18° C. or 64 F.; altitude 1,3-il metres or 4,400 feet), 

 all the following species were seen or taken Aug. 6 and 7, 1906: Argia moesta, 

 Enallagma civile, Ischnura ramhuri var. credulu, Anax {Junius?), Plathemis 

 subornata, Orthemis ferruginea, Tramea sp., Pantala flar^escens, Sympetrum cor- 

 ruptum, Erythemis simplicicollis or its subspecies collocata. 



Mazatlan (Pacific sea-coast, mean annual temp. 1880-1902, 24.9° C. or 76.8° 

 F.; mean ann. rainfall 1880-1901, 806 mm. or 32.25 inches): Mecistogaster 

 ornatus, Argia pulla, Enallagma caecum novce-hispanice, Leptobasis vacillans, 

 Ischnura ramburi and var. credula, Pseudoleon superbus, Orthemis ferruginea, 

 Erythrodiplax funerea, Brechmorhoga postlobata, Macro^/iemis inacuta, Miathyria 

 marcella, Tramea longicauda var., T. onusta, Pantala flavescens, P. hymencea, 

 Perithemis domitia intensa, Cannacria batesii, Erythemis verbenata, Lepthemis 

 vesiculosa. 



Atoyac, Vera Cruz (moist Atlantic slope of Mexico, cf. page 480 antea; mean 

 ann. temp, probably about 22.7° C. or 72.9° F. ; alt. 400 m. or 1,314 ft.) : Hetwrina 

 cruentata, H . iltia, H. macropus, W. infecta, Cora marina, Archilestes grandis, Lestes 

 tenuatus, Meguloprepus coerulatus, Pseudostigma aberrans, Mecistogaster ornatus 

 and modestus, Hcteragrion chrysops, Hyponeura funcki, Argia perceliulata, trans- 

 lata, frequentula, ulmeca, oculctta, cuprea, oenea, fissa and exfranea, Anisagrion 

 lais, Enallagma cop.cum novce-hispanice, Acanthagrion gracile, Leptobasis vacillans, 

 Palsmnema paulina and angelina, Protoneura aurantiaca, Qomphoides suasa! 

 Erpetogomphus viperinus and ophibolus, Cyanogomphus (?) tumens, jEshna 

 cornigera, virens and perrensi, Gynacantha trifida and tibiata, Libellula herculea, 

 Pseudoleon superbus, Tholymis citrina, Micrathyria didyma, dissocians and ocellata, 

 Orthemis ferruginea and levis, Cannaphila vibex, Anafya guttata, Erythrodiplax 

 funerea, umbrata, ochracea, connata vars. d and e, Dythemis velox, Brechmorhoga 

 vivax, prarox, pertinax, and inequiunguis , Macrothemis pseudimitans and hemi- 

 chlora, Miathyria simplex, Tauriphila azteca, Perithemis domitia iris and d. mooma, 

 Erythemis peruviana, attala and verbenata, Lepthemis vesiculosa. 



Puerto Barrios (Atlantic coast of Guatemala, see page 480; mean ann. temp, 

 for 1896, 26.8° C. or 80.3° F.): Hetxvrina tricolor, titia and miniata, Hcteragrion 

 chrysops, Argia translata, gaumeri, frequentula and indicatrix, Acanthagrion 

 (/?-aci7e,Telebasis digiticollis, Anomalagrion hastatum, Ceratura capreola, Neoneura 

 paya, Protoneura amatorla, Ephidatia longipes cubensis, Uracis imbuta, Micra- 

 thyria debilis and eximia, Nephepeltia phryne, Anatya normalis, Erythrodiplax 

 umbrata, ochracea, connata vars. c, d, e, Dythemis velox, Macrothemis hemichlora, 

 Tauriphila argo, Tramea insularis, Pantala flavescens, Perithemis domitia iris, 

 Erythemis verbenata, Lepthemis vesiculosa. 



San Geronimo' (dry, elevated central Guatemala; mean ann. temp, probably 

 20°-21° C. or 68°-69.8° F.; mean ann. rainfall less than 1,000 mm. or 40 inches; 

 alt. 900 m, or 2,950 ft.): Hetwrina cruentata, capitalis and rudis, Amphipteryx 



'^ Biol. Centr.-Amer. Neurop., pp.- 387-389. 



