DESCKIPTIONS OF AUSTRALIAN ^SCHNIN^, 71 



proved to belong to this genus, though Needham *, in speaking of the larva 

 of Stavroph/ehia, says that it is " very like that of the nyinph of Gpiacantha, 

 and quite different from that of other known ^schnince " ; these differences 

 being chiefly the " upcurved, sharp, and spinulose " distal margins of the 

 mentum, the bilobed spine-bearing median lobe, and the sharply-pointed 

 hook-like apices of the lateral lobes of the labium. 



In February 1910 the late Mr. H. Elgner discovered the larva3 of Gyna- 

 cantlia rosenhergi on Banks Island, Torres Straits, and sent me three exuvise, 

 together with a newly-emerged imago taken from one of them. Even 

 without the latter evidence, the extraordinary length of the involucres of 

 the imaginal appendages would at once have determined the genus to which 

 these exuvise belonged. I began to study them, expecting to find a labium 

 similar to that of Stauroplilebia ; but I was quite astounded to find that the 

 labium was almost exactly like that of vEschna brevistt/la, except that the 

 lateral lobes each carried a strong and well-developed set of setca corresponding 

 in size and position to those found in the nymphs of Libellulidse. This 

 discovery was very startling and unexpected. If, as seems to me probable 

 this character is to be found in the nymphs of other species of this genus, 

 and possibly in those of allied genera, then Needham's reference to a 

 " Gynacantha nymph " is certainly quite inexplicable, and suggests an error 

 in determination. 



It is much to be hoped that no time will be lost in searching for other 

 nymphs of this genus, many species of which are abundant enough in 

 tropical regions. 



„ Gynacantha eosenbergi, Brauer. (Plate 4. fig. 10.) 

 Brauer, Verb, zool.-bot. Ges. Wien, xvii. (1867) p. 290. 

 Gynacantha bonguensis, Forster. 



Larva. — Total length 41 mm. ; greatest breadth 8 mm. across eyes. 

 Head. — Flat above, with lavge eyes and smooth rounded postocidar lobes. 

 L a b i u m. — Mentum 7*5 x 4'5 mm., reaching back to well between mesocoxsej 

 where it narrows to barely 2 mm. (Plate 5. fig. 16). Median lobe very 

 slightly bilobed, with a fairly deep median cleft fringed with a row of short 

 hairs. Lateral lobes shaped as in y^schna, but somewhat shorter and wider ; 

 apex very flatly truncated, with outer angle scarcely at all rounded and 

 inner angle sharply toothed ; no crenulation of inner margin ; movable hook 

 1*6 mm. On a raised ridge running slantwise from below the movable 

 hook across the middle of the lobe is a set of 8-9 very conspicuous setce, the 

 first apical five of which are long (three reaching to about the outer angle of 

 the apex) ; the sixth is of medium length, and the last two or three, lying 



* 'New Dragonfly Nymphs in U.S. Nat. Museum/ 1904, p. 694. 



