Nov., '08] ENTOMOLOGICAL NEWS. 431 



hind wing; Group IV has 8-12 cross-veins in front wing and 

 4-5 in hind wing. 



Of the three genera with 4-sided triangles in the front wing, 

 Cordulephya is remarkable by the great divergence of M 3 

 and M 4> and the convergence of M 4 and Cui in the front 

 wing, and the reduction of wing area. It suggests Syncordulia. 

 Neophya is its exact opposite in all these characters and sug- 

 gests Idionyx. Pentathemis has as little in common with the 

 other two as they have with each other, the 4-sided triangle of 

 the front wing resulting from an entirely different switching of 

 veins. It is related to Aeschnosoma and perhaps should be 

 placed in the same group. 



PLATYCORDULIA new genus.* 



Related to Neurocordulia, Aeschnosoma and Libellulo- 

 soma. Distinguished at once from all by the apically broad- 

 ened and rounded anal loop which is widely sep- 

 arated from the wing margin by 2 rows of cells (one row 

 in all the others) . Of the four genera it has the densest reticula- 

 tion. The two genera Aeschnosoma and Libellulosoma are close- 

 ly related to each other and are distinguished from the other two. 

 among other characters, by the strongly waved Ms and M 4 

 in both front and hind wings and the unsymmetrical and pecu- 

 liar forking of MI and M 2 in both front and hind wings. 

 Two species of Neurocordulia are known. The venational dif- 

 ference between them is slight, consisting of a greater number 

 of antenodals in both front and hind wings in yamaskanensis 

 as compared with obsoleta and scarcely definable differences in 

 the form of the anal loop (differences in the form of the two 

 distal angles and the direction of the distal side with reference 

 to the long axis of the wing). Some of the venational differ- 

 ences between the two species of Neurocordulia and Platy- 

 cordulia xanthosoma n. sp. are discussed below. The denser 

 reticulation of Platycordulia is a striking character, recognized 

 at once by the increased number of rows of cells between the 

 sectors at a relatively proximal position in the wing. Type of 

 riatycordulia: P. xanthosoma, n. sp. 



* The name refers to the broadened anal loop in the hind wing. 



