460 PROCEEDINGS OF THE ACADEMY OF [Oct. 



THE COMPOSITION AND ECOLOGICAL RELATIONS OF THE ODONATE FAUNA 

 OF MEXICO AND CENTRAL AMERICA. 



by philip p. calvert. 



Contents. 



General Conditions determining Odonate Distribution. 



The Chief Odonatological Features of Mexico and Central America. 



Relations of the Mexican-Central American Odonate Fauna to those of other 



Areas. 

 Distribution of the Odonata within limited portions of Mexico and Central 



America. 

 Relations of the Odonate Fauna of Mexico and Central America to Temperature, 



Rainfall, Vegetation Areas and Altitude. 



The preparation of an extended account^ of the Odonata of Mexico 

 and Central America has induced me to study the relations of these 

 insects to various factors of their environment, with the results here 

 set forth. The facts on which this study is based, in so far as the 

 Odonata are concerned, are contained in the Biologia volume, to 

 which reference must be made for further details. Since the comple- 

 tion of that work, I have received, through the kindness of Mr. H. T. 

 Van Ostrand, specimens of Enallagma prcevarum, Opionceschiia armata 

 and Sym'petrum, illotum virgulum, taken at or near Real del Monte, 

 Hidalgo, Mexico, which add to our knowledge of the distribution of 

 these three species as given in the Biologia. The first and third are 

 labelled as having been captured at 9,000 feet elevation, or the highest 

 altitude yet recorded for Odonata in Mexico or Central America. 

 These additional data are included in the following pages. 



General Conditions Determining Odonate Distribution. 



The actual distribution of the Odonata is determined by the con- 

 ditions under which their aquatic larvae are able to exist. The dis- 

 tribution of the larvae, so far as the present region is concerned, is almost 

 entirely unknown. Our present information refers to the appearance 

 of the imagos in certain localities, and the summary herewith presented 



^ Odonata, by P. P. Calvert, forming pp. 17-420 and Introduction, pp. v-xxx 

 of volume Neuroptera of the Biologia Centrali Americana, edited by F. D. God- 

 man. London, 1901-1908. 4to. 9 plates, 1 map. 



