414 Mr. R. M'Lachlan on some Odonata 



narrow at the base, then gradually dilated, followed by a long 

 excision and again gradually dilated to the apex, which is 

 somewhat rounded, ending externally in a sharp tooth or 

 spine ; a dense fringe of long hairs nearly from base to apex 

 internally. Inferior appendage less than one third the length 

 of the superior, elongately triangular, obtuse and scarcely 

 emarginate at apex, concave and yellowish above. 



"Wings hyaline, slightly fumose, more or less uniformly 

 tinged with brownish when very adult ; a brownish mark at 

 extreme base, extending a short distance along the subcostal 

 and median areas; pterostigma reddish brown (5 millim.), 

 surmounting 5^ to 6| cellules ; membranule rudimentary, 

 whitish ; neuration very dense, blackish, costal edge dark 

 purplish externally ; subnodal sector furcating before the level 

 of the pterostigma, the cellules between the branches com- 

 mencing as one, then two, followed by three, five on the 

 margin ; 7 cellules between the subnodal and interposed 

 sector in the broadest part, ending in two marginal cellules; 

 one row between the sectors of the triangle in both pairs ; 

 no basal subcostal nervule (exceptionally one in a posterior 

 wing) ; 28 to 30 antenodals and 24 postnodals in the anterior 

 and 25 to 27 and 24 to 26 in the posterior ; 6 to 9 cellules in 

 the principal triangle, 2 in the inner ; 8 to 10 supra- trigonals ; 

 6 nervules in median area; 6 (exceptionally 5) cellules in 

 anal triangle (two above, three in the middle, and one below). 



Length of abdomen (cum append.) 59-60 millim. ; length 

 of posterior wing 50-53 millim., greatest breadth of same 

 16-17 millim. 



Bab. Mougo-ma-Lobah, Cameroons (Rutherford), two 

 males. 



Quite distinct from other West-African species by the form 

 of the appendages, the 6-celled anal triangle (which is per- 

 fectly constant in internal arrangement in three of the four 

 wings examined), and the brown markings at the base of the 

 wings. 



Gynacantha quadrina, sp. n. 



$ . Face dingy yellowish, margin of labrum and the nasus 

 somewhat fuliginous ; a black T-spot on the top of the front, 

 the tail of which is very distinct and the top ill-defined, the 

 whole placed in a deep sulcus (longitudinal and transverse) ; 

 eyes connected in a long space, occiput rather elongate, dingy 

 yellowish, its margin elevated; back of head dingy yellowish. 

 Thorax brownish fuliginous above, paler anteriorly, with 

 cinereous pilosity ; sides dingy ochraceous, together with the 



