24 Mr. R. M‘Lachlan on some 
tiguous or united blackish spots on the posterior half ; second 
whitish yellow at the anterior margin and on an anterior 
triangular space, and again on each side towards the posterior 
end; third to sixth with a whitish-yellow narrow anterior 
annulation, and a broader one before the posterior end ; tenth 
segment and appendices conspicuously whitish in both sexes ; 
on the sides the abdomen is almost wholly whitish yellow, 
shading into smoky, but the posterior ends of segments 3 to 7 
are broadly of the dark colour of the upper surface. 
6. Posterior margin of tenth segment with a broad semi- 
circular excision, furnished with numerous minute black teeth. 
Superior appendages of the length of the tenth segment, 
geniculate in the middle; the outer edge (beyond the genicu- 
lation) with 3 to 4 small but conspicuous black teeth; internally 
the basal portion is dilated, and forms an obtuse angle before 
the constriction at the geniculation; the apical portion again 
gradually dilated, and with a long acute tooth before the obtuse 
apex, which latter is darker in colour. Inferior appendages 
very short, in the form of two contiguous broadly triangular 
plates fringed with whitish hairs. 
?. Posterior margin of the tenth segment with a broad 
shallow excision with black denticulations; appendages 
shorter than the tenth segment, in the form of acute styles ; 
the ventral laminz broad, strongly denticulated beneath, the 
appendages filiform and upcurved. 
Length of abdomen, g (cum append.) 32-34 millim., 
¢ 29 millim.; expanse of wings, ¢ 34-89 millim., 9 
40 millim.; length of posterior wing, g 19-21 millim., 
9 20 millim. 
Hab. Aru Islands and New Guinea. Two males and one 
female from the Wallace collection; formerly examined by 
M. de Selys, and labelled by him with the name I have 
adopted. 
Probably allied to the Australian group of species. 
Lestes tridens, sp. n. 
Wings hyaline. Pterostigma smoky brown, rather more 
than twice as long as broad, surmounting two cellules ; 9-10 
postnodal cellules in the anterior wings. 
Head dark brown above ; labrum olivaceous ; labium pale 
yellowish ; back.of head blackish near the eyes, but yellowish 
more internally. Prothorax dusky testaceous, darker at the 
sides and there somewhat pruinose. Thorax ochreous: a 
rather broad black band on either side of the dorsal crest, its 
edge nregular externally, and there showing two broad 
