1899.] NATURAL SCIENCES OF PHILADELPHIA. 245 



PARALLELISMS IN STRUCTURE BETWEEN CERTAIN GENERA OF 

 ODONATA FROM THE OLD AND THE NEW WORLDS. 



BY PHILIP P. (,'ALVERT, PH.D. 



The African genus Pseudomacromia Kirby has been compared 

 by Dr. Karsch^ with the neotropical Macrothemis Hageu. In the 

 identification of the species of P'seudomacromia (P. Donaldsoni n. 

 sp. ), described in the preceding paper, I have studied the other 

 species of this genus, as well as those of the genera Zygonyx Selys 

 and Schizonyx Karsch, chiefly with the view of learning to what 

 extent these three Old World groups parallel, in their structure, the 

 New World Macrothemii and its allies. As a basis for this com- 

 parison I have used a recent paper,- in which I have shown that 

 the five American genera Dythemis, Paltothemis, Scapanea, Brech- 

 morhocja and Macrothemis form a group (of the subfamily Libel - 

 luliure), the chief pecuUarity of which is " the modification of the 

 armature of the second and third femora in the males, and of the 

 tarsal nails in both sexes," the details of the modification being 

 characteristic for each genus, Dythemis being the least modified, 

 Macrothemis the most modified of the five. 



The reason for the comparison of Schizonyx, Pseudomacromia 

 and Zygonyx with Macrothemis, etc., is that they show similar 

 modification of the femoral armature and of the tarsal nails. 



The following species are referred to these three genera respec- 

 tively : 



To Schizonyx Karsch, luctifera Selys (type of the genus) ; 



To Pseudomacromia Kirby, torrida Kirby (type of the genus), 

 Donaldsoni Calvert, hova Rambur, speciosa Karsch and pretiosa 

 Karsch f 



1 Eatomologiscbe Nacbrichten, xvii, p. 73, 1891 ; Berlin, Eat. Zeits., 

 xxxviii. p 21, 1893. 



^ The Odonate Genus MacrotJiemis and its Allies. Proc. Bost. Soc. Nat. 

 Hist., xxviii, pp. 301-332, 2 pis., July, 1898. 



3 Speciosa and pretiosa, described from male and female respectivelj, are 

 perhaps one and the same species, for Mr. ]McLachlan writes me, under date 

 of March 3, 1899 : " I come round to the opinion that these are probably 



