ON THE OSMYLIN.E OF JAPAN. 



Dictyosmyhis to be synonyms of Osmylus. Moreover, I think that 

 Kriiger's Plethosmyhis is also to be made a synonym of it. 0. 

 hyalinatus M'L., for which he made that new genus, is a species 

 which stands very near to the type of Osmylus, O. maculatus F., as 

 was pointed out by MacLachlan. 



Consequently, the genus should in my opinion be defined as 

 follows : 



Three ocelli present, placed close together. Legs with entire 

 empodia ; a spur exists on coxa I in female of most species. Wings 

 broad ; media of fore wing forked near base ; costal cross-veins mostly 

 furcate, sometimes two adjoining veins cross each other or are con- 

 nected by a short cross- vein ; cubitus of both wings has a branch 

 running parallel to it for a considerable distance. 



The structure of coxa I, which had never before been used for 

 the systematic purpose by any entomologist except Needham (I.e.), 

 who utilized it for generic distinction, seems to afford a useful differ- 

 ential character for the distinction of species. All the Japanese species 

 of the genus may be distinguished thus : 



r. Coxa I without spur, but with a somewhat dilated portion 



instead , tessellattis. 



Coxa I with spur 2. 



2. The spur crooked Pryeri. 



The spur not crooked 3. 



3. The spur rather long, not directed upward, nor dilated at 

 apex hyalinatus. 



The spur short, directed distinctly upward and dilated at 



apex decoratus. 



Osmylus tessellattis MacLachlan. Fig. 2. 



Osmylus tessellattis M'Lachlan, Trans. Ent. Soc. Lond., ii, p. 180 

 (1875). 



1) So far as known, the spur is peculiar to the female. 



