Mar., 1909.1 OsBURN : Odonata Biologia Centrali-americana. 39 



THE ODONATA OF THE BIOLOGIA CENTRALI- 

 AMERICANA.* 



By Raymond C. Osburn, 

 New York City. 



The final section of this admirable work by Professor P. P. Calvert, 

 of the University of Pennsylvania, made its appearance near the close 

 of 1908, marking the completion of a research extending over nearly a 

 decade for Professor Calvert, after it had been successively undertaken 

 and abandoned by McLachlan, Hagen and Karsch. Dr. Calvert 

 began this work in 1899, and the first section appeared in 1901. 

 The complete work consists of an introduction of 25 pages, dealing 

 chiefly with distribution and sources of material ; the body of the work, 

 325 pages, and a supplement of 68 pages, dealing with additional ma- 

 terial received too late to be incorporated in the main part. A very 

 complete index, including all synonymic names, follows. The nine 

 lithographed plates include 404 figures, showing the essential features 

 of all the new, as well as of many hitherto imperfectly known species. 

 The region covered by this report comprises all the Central 

 American States, with Panama on the south, and Mexico, with the 

 immediately adjoining parts of Texas, New Mexico, Arizona and Cal- 

 ifornia, which present the same climatic conditions as northern Mex- 

 ico, on the north. These limits include a very natural area of distri- 

 bution for the Odonata, plainly marked off from the West Indies also, 

 as the analysis of the data indicates. The list for this area includes 

 71 genera, embracing 293 species and varieties, and of this list 18 

 genera are represented by species found only in this region, and 143 

 species, almost half the entire number, are not known to occur 

 elsewhere. 



A comparison of the dragonfly fauna of this area (to which we may 

 refer briefly as the " central" region) with that of the rest of North 

 America ("northern" region) yields some interesting results. The 

 number of species at present known from the two regions is approxi- 

 mately the same, notwithstanding the much greater area of the northern 

 region, but the number of genera in the central region is considerably 

 in excess of that in the northern. The proportions of the species in the 



* A review, read before the N. Y. Ent. Soc. at its meeting on January 5, 1909- 



