THE SUBFAMILY LIBELLULIN^E. 329 



tinuous ; triangle followed by three cells, increasing, the upper sector rising a little 

 before the apex, and distinctly separated from the lower, which is not the case in 

 typical Trithernis. Wings hyaline, more or less yellow at the base in the female and 

 immature male ; in the mature male there is a large roundish brown smoky spot near 

 the centre of each wing, varying in size, and another at the base of the hind wings, 

 which, in the darkest specimens, is suffused with the outer one. 

 Hah. Santarem. 



Trithemis C?) lacustris. 



Long. corp. 28 millim. ; exp. al. 48 millim. ; long. pter. 2 millim. 



Male. — Red, the upper part of the head rather darker, and coarsely punctured ; 

 ocelli conspicuously black; frontal tubercle, cheeks, and lower mouth-parts varied 

 with yellow, pectus rather irregularly spotted with black, and femora black above 

 nearly to the knees. Wings hyaline, with reddish nervures, smoky yellow at the base 

 for more than a third, the colour extending on the hind wings nearly to the nodus ; 

 fore wings with 9 antenodal and 7 postnodal cross nervures, the last antenodal and 

 the first three postnodals not continuous ; pterostigma rather long, very pale yellow, 

 between thick black nervures, and slightly clouded at the extremity ; fore wings with 

 the triangle traversed, followed by three rows of cells, increasing, subtriangular space 

 consisting of two cells ; hind wings with 6 antenodal and 6 or 7 postnodal nervures, 

 the first three postnodals not continuous ; the triangle followed by two rows of cells, 

 increasing, its sectors rising together. 



Hah. Wadelai, Central Africa; collected by Emin Pasha 1 on Jan. 27, 1887. 



This species has a superficial resemblance to Trithemis sanguinolenta, Burm. ; but in 

 many characters it resembles the genus Cacergates. 



Brachydiplax ixdica. (Plate LIV. fig. 9.) 



Long. corp. 29-32 millim. ; exp. al. 50-54 millim. ; long. pter. 3 millim. 



Front and frontal tubercle entirely blue or greenish blue, strongly punctured ; face 

 yellow, the extremity of the labrum, the mandibles, except a spot at the base on 

 each side, and the sutures of the labium broadly black ; back of the head entirely 

 black, except two small contiguous yellow spots behind the occipital triangle, and a 

 yellow crescent just above the neck. Thorax black above, pruinose in the adult male ; 

 the pleura coppery green, marked in the adult male with a yellow spot about the 

 middle, a yellow streak beyond, and the extremity yellow ; in the immature male 

 there is a yellow stripe on the side just in front of the wings, extending almost to the 

 back, two stripes, the second interrupted, below the first pair of wings, and the hinder 



1 The only other Odonata sent home by Emin Pasha in his last collection belong to Palpopleura portia, 

 Dru., Cacergates leucostkta, Burm., and Ischnura senegalensis, Rarnb., three very common and widely distributed 

 African species. 



vol. xii. — part tx. No. 11. — August, 1889. 3 b 



