466 PROCEEDINGS OF THE ACADEMY OF [Oct., 



results for Reptiles and Batrachia: "The plateau seems to be a much 

 more effective barrier to the southerners than is the descent into the 

 hot lowlands to the northern creatures."* 



The West Indies lie within the same parallels of latitude as do Mexico 

 and Central America. The total number of species of Odonata found 

 in those islands is about 91;^ 56 of these, or 61.5%, also occur in our 

 present district. The number of species common to both is likely 

 to be increased by future explorations, especially as the Odonate 

 fauna of Yucatan and British Honduras, the continental areas lying 

 nearest to the West Indies, is very imperfectly known. But, making 

 use of the present figures, it is rather surprising that only 61.5% of 

 the West Indian Odonata are found in Mexico and Central America, 

 seeing that the prevalent winds on the east coast of the mainland are 

 easterly (i.e., northeast, east and southeast).^" With such insects 

 as the Odonata one might expect the winds to play an important part 

 as means of dispersal." The West Indian species not yet found in 

 Mexico or Central America include a number of fair-sized and prob- 

 ably fair-flying species, e.g., Aphylla produda, Progomphus integer 

 and serenus, Dythemis rufinervis, Scapanea frontalis, Macrothemis 

 celceno, Celithemis eponina, etc. 



The extent to which species common to the West Indies are found 

 in some parts of Mexico and Central America is shown in Table 3. 



The Endemic Genera and Species are summarized in Table 4, p. 468. 



Of the genera listed in Table 4 as occurring in both Northern and 

 South America, Hetcerina, Argia, Progomphus, Erythrodiplax, and per- 

 haps Dythemis, are represented by a greater number of species in South 

 America than in Northern America, and these genera are entirely, 



8 Proc. Zool. Soc. London, 1905, II, p. 239. 



»Hagen, Proc. Bosi. Soc. Nat. Hist., XI, pp. 289-294 (1867); XVIII, pp. 

 20-96 (1875). Uliler, I.e., XI, pp. 295-298 (1867). Kolbe, Archiv /. Naturges., 

 LIV, I, pp. 153-178 (1888). Ivirby, Ann. and Mag. Nat. Hist., (6) XIV, pp. 

 261-269 (1894). Carpenter, Journ. Inst. Jamaica, II, pp. 259-263 (1896). 

 Calvert, Biol. Cent. Amer. Neurop. Introd., Table B (1908). 



'° See the charts of prevailing winds accompanying Buchan's Challenger 

 Report on Atmospheric Circulation, and the data given in Table VII of the 

 Appendix thereto, pp. 169, 170, for Matamoras and Cordova, Mex., and Belize; 

 also the data for Merida, Campeche and Jalapa by Moreno y Anda and Gomez 

 in El Clima de la Eepublica Mexicana, Ano I (for 1895) and II (for 1896), Mexico 

 City, Secretaria de Fomento, 1899 and 1900. Cf. also Sapper, Mittelameri- 

 kanische Reisen und Studien, Braunschweig, 1902, p. 297. The Challenger data 

 for Blewfields, Nicar., I.e., p. 171, represent the prevailing wind as northwest, 

 which has Uttle bearing on the question of the relations of the continental and 

 West Indian Odonata. 



" On the other hand Chapman states that of the 550 species and subspecies 

 of birds recorded from the West Indies, 303, or 55%, are endemic. Bull. Amer. 

 Mus. Nat. Hist., IV, p. 318, 1892. 



