Oguma, The Japanese Dragonfly-Fauna of the Family Libellulidae. 97 



Next I give a brief account on the distribution of the 

 Libellulidae in Japan. The 72 species, viz. 50 known and 22 new, 

 can be divided into two regional groups : the P a 1 a e a r c t i c or 

 northern species and the Oriental or southern species. The 

 former occur in the northern part of Japan viz. northwards from 

 Kiushiu, showing connexion with the fauna of the northern Asiatic 

 continent , while the latter are restricted in their occurence to 

 the Loo-Choo group, holding very intimate relation to the fauna 

 of Indo-Malayan region and of Australian region. At Okinawa 

 and Kiushiu both the northern and southern species overlap each- 

 other.to some extent. 



The strait of Tsugaru , which is known as Blakiston's line, 

 acts no powerful barrier on the distribution of Libellulidae, since 

 the same species are very often found on both sides of strait. 

 In this respect Hokkaido is connected also with Saghalin. Further 

 no distinction is between the fauna of Siberia and that of Saghalin. 



Descriptious of a new Genus, Species and Snbspecies. 



RhyiotJiemis nebulosa sp. nov. 



Abdomen 21 mm; bind wing 31 mm; pterostigma 2 mm. 



Male. Head: black with violet reflection above and a 

 yellowish streak at the base of clypeus. 



Thorax: black with greenish reflection. Wings rather 

 narrow, brown, with weak reflection of violet and with a hyaline 

 transverse band at the distal part of nodus dividing a wing into 

 two colored parts, but in the bind wing this hyaline band sepa- 

 rates itself by the middle constriction in two speaks of irregulär 

 shape. All of the hyaline parts with their borders not sharply 

 defined from the colored parts. N e r v u r e s and pterostigma 

 brown. Legs fuscous. 



Abdomen: black ; upper anal appendages nearly as long 

 as the 9*^ segment , distal portion considerably thickened and 

 truncated terminally ; lower appendage nearly four fifths of the upper. 



F e m a 1 e : unknown. 



Nom. Jap.: Kumogata-cho-tombo. 

 Loc. : Loo-Choo (Uchida). 



Sympetrum gracile sp. nov. (PI. II, Fig. 1 — 4.) 

 Abdomen cf 20 mm , $ 22 mm ; bind wing cf 24 mm, 



? 27 mm ; pterostigma cf ? 2 mm. 



Male. Head: frontal tuber cle and the basal part of frons 



metallic black ; face white, being often somewhat yellowish, finely 



haired , with a black patch on frons ; labrum and labium pale 



yellow. 



Deutsche Entomol. Zeitschrift 1922. Heft I. 7 



