THE SUBFAMILY LIBELLULIN.E. 321 



triangle rather broad, crossed by two nervures on one side and by three on the other 

 (in the latter, the second cell from the tip is longitudinally bisected), and followed 

 by five rows of discoidal cells (first row on one side of four only). Subtriangular space 

 consisting of eight cells. Anal appendages short but distinct, slightly curving upwards, 

 and acuminate. 



II ah. Sierra Leone. 



Rhyothemis obsolescens. 



Long. corp. 24 millim. ; exp. al. 46 millim. ; long. pter. 2 millhn. 



Male. — Allied to B. f id gens, but with the wings, especially the hind wings, rather 

 longer and narrower. Upper part of the head and labium bronzed, face otherwise 

 testaceous. Thorax and abdomen blue-black. Legs wanting. Appendages of the 

 second segment of the abdomen not prominent. Upper anal appendages rather shorter 

 than the last two segments, slender at the base, curving downwards, thickened at the 

 extremity, and not sharply pointed. Lower appendage three fourths as long as the 

 other, very slender, curving upwards, and with a very conspicuous excrescence on the 

 upper surface, just before the middle. Wings brown, slightly iridescent; fore wings 

 with 8 antenodal and 5 postnodal nervures (the last antenodal nervure is not continuous, 

 but there are, nevertheless, 8 in the lower space, where an additional nervure is inter- 

 calated between the fourth and fifth). The antenodal nervures of both the subcostal 

 spaces of the fore wings form the diagonals of nearly square dark spots, set obliquely 

 to the costa. Beyond the nodus, the spaces before the third postnodal nervure, and 

 the spaces below, to beyond the subnodal sector, form a large pale triangle; and all 

 the cells around the pterostigma, and between the postnodal nervures of the upper 

 space, and the last two nervures of the lower space are likewise paler. On the hind 

 wings the costal markings are nearly similar, but the hind margin is pale from the 

 anal angle to just beyond the subnodal sector, and there are two pale bars running 

 from the middle of the inner margin to about one seventh of the length of the wing, 

 the uppermost nearly straight, the lower one narrower, curved upwards, and with a 

 third short pale streak below its inner extremity ; a little beyond the triangle is like- 

 wise an ill-defined pale space. Triangle of the fore wings divided by two nervures, 

 and followed by five rows of cells (four in the first row on one side, owing to the 

 disappearance of a nervure). Subtriangular space consisting of six cells. 



Rah. Borneo. 



This species is interesting as forming a connecting link between the sections repre- 

 sented by B. pliyllis, Selys, and B. pycjmwa, Brauer. The pale markings in B. obso- 

 lescens correspond to the yellow markings of the hind wings in the former group. 



vol. xii. — part ix. No. 10. — August, 1889. 



