NO. 1571. DRAQONFLIES OF BVRMA AND SIAM— WILLIAMSON. 



285 



thoracic pattern, by the more extensive yellow on abdominal segments 

 3-6, and by the very different appendages. From javanica by having 

 the subtriangle of front wing divided, not free; by the more extensive 

 yellow on abdominal segments 3-6, and b}^ the form of the appendages. 



Genus SIEBOLDIUS De Selys. 



Three species have been described in this genus. All are large 

 insects, abdomen 55-61 mm., hind wing 47-55 mm. S. alhardse, 

 De Selys occurs at Pekin; japjjonicus De Selys is known from Borneo 

 and the Malay Peninsula; and grandis Kriiger has been described 

 from two females from Sumatra. S. graiidis is based largely on 

 characters of the occiput and it remains to be seen if the species is 

 separable from, jajj'ponicus. Ijaidlaw's record of grandis from the 

 Malay Peninsula should really be ja'pi)onia(s, I believe. 



5. SIEBOLDIUS JAPPONICUS De Selys. 



Four males, Khow Sai Dow Mountain, 1,000 feet, Trong, I^ower 

 Siam, Jan.-Feb., 1899, Dr. W. L. Abbott, collector, collection 

 U.S.N.M. One of these is teneral. All agree with De vSelys's descrip- 



FiG. 11.— Wings of male Sieboldius japponicus from Siam. 



tion in Odonates du Japon and with Laidlaw's description of a male 

 "caught at the foot of Gunong Inas (about 1,000 feet above sea level) 

 near a small jungle pool, in January, 1900." (See fig. 11.) 



