Odonatafrom Queensland. 19 



black nervures, triangle not traversed, followed by two rows 

 of cells, increasing; subtriangular space consisting of one 

 cell ; hind wings with the base of the triangle not quite coin- 

 ciding with the arculus. 



Described from a single male specimen. If this was 

 completely mature the blue pulverulescence would probably 

 obliterate all trace of yellow markings ; but the female and 

 newly-emerged male are both probably yellow and aqueous 

 black, without any trace of blue. 



This is the first species of the genus described from 

 Australia. It is probably allied to B. denticauda, Brauer, &c. 



Zyxomma petiolatum. 



Zyxomma petiolatum, Ramb. Ins. N<5vr. p. 30 (1842). 



A single specimen, perhaps a little darker than Indian 

 specimens, but otherwise hardly differing from them. 



Orthetrum sabina. 

 Libelhila sabina, Drury, 111. Ex. Ent. i. pi. xlviii. fig. 4 (1773). 

 An abundant species from India to Australia. 



Orthetrum nigrifrons, sp. n. 



Long. corp. 46 millim. ; exp. al. 70 millim. ; long. pter. 

 5 millim. 



Male. — Head black, sutures of the rhinarium and labrum 

 yellowish, face smooth and shining, frontal tubercle bifid, 

 thorax black or blue-black, abdomen blue, legs black. Wings 

 clear hyaline, very narrowly stained with saffron at the base 

 of the hind wings ; pterostigma long, yellow, between black 

 nervures, not remarkably thickened, nervures mostly blackish, 

 except the costal nervure between the nodus and pterostigma, 

 which is testaceous ; it is also testaceous in front from the 

 base to the nodus : fore wings with eleven antenodal cross- 

 nervures, the last not continuous, and with nine or ten post- 

 nodal nervures, the first two not continuous ; triangle mode- 

 rately long and broad, followed by three rows of cells 

 increasing ; subtriangular space consisting of three cells j 

 no supra-triangular nervules, nodal and subnodal sectors not 

 much waved ; hind wings with the triangle not traversed. 

 Anal appendages of moderate length ; the lower one broad, 

 truncated, nearly as long as the others. 



Described from two male specimens. Much resembles 

 0. triangularis, De Selys, but smaller, and the want of 



