COLLECTED I]^ DUTCH NEW GUINEA. 489 



Subfamily Libellulinae. 

 Tetrathemis irregulakis leptoptera Selys. 

 1 d . Utakwa Eiver, Feb. 1913. 



Genus Oda Ris. 

 (Collections Selys, LibelL, £asc. ix. pp. 18 & 61, 1909.) 

 This genus was established for the reception of the single species ]Vannoj>klebia (1) 

 dohrni Kriiger from Sumatra. Other specimens have been obtained in Borneo, and 

 there is a record, which needs confirmation, of a female from the Marianne Islands. 

 To the same genus may now be added a second species, which resembles the type- 

 species very closely in general appearance. For purposes of comparison, I have had 

 before me a male and female of Oda dohrni, in fine condition, kindly lent to me by 

 Mr. F. F. Laidlaw (Matang Road, Sarawak, Borneo, 9. xi. 09, J. C. Moulton). 1 have 

 also referred to Dr. F. Eis's photographs reproduced in the above-named work as 

 figures 25 (left wings of 6 ), 26 (left wings of ? ), 27 (segment 2 of J ), and 28 

 (anal appendages of d ). 



The new species has been referred to Oda upon the advice of Dr. Ris, notwith- 

 standing its disagreement with 0. dohrni in several important characters. Its inclusion 

 therein will necessitate some modification in the definition of that genus as given by 

 its author, and the following description has been made to cover all the characters 

 which must be taken into account whenever the genus is re-defined. 



I have great pleasure in dedicating tlie interesting new species to Dr. F. Ris, 

 to whom I am indebted for much valuable assistance in studying its characters 

 and affinities, as well as for kind help with other difficult species contained in the 

 present collection. 



Leaving venational characters out of account for the moment, the males of the two 

 known species of the genus may be separated thus : — 

 Abdominal segments 1, 2, and 3 very large, followed by a sudden constriction ; 

 iabrum black ; tibise of hind-legs black ; a broad black band lying on tlie 



second lateral suture of the thorax dohrni Kriiger. 



Abdominal segments 1, 2, and 3 not inflated or followed by any constriction ; 

 Iabrum bright yellow ; tibiaj of hind-legs yellow ; no black band on the 

 second lateral suture of the thorax risi, sp. n. 



Oda risi, sp. n. (Text-fig. 40.) 



1 s . Utakwa River, Feb. 1913. {Type of the species.) 



6 , holotype (not fully matured, head flattened by pressure, and abdomen somewhat 

 crushed). Length of abdomen, including anal appendages, 19"5 mm.; length of 

 hind wins: 22 mm. 



