240 Mr. H. Campion on some 



XXV. — So7ne Dragonflies and their Prey. — IT. With Re- 

 marks on the Identity of the Species of Oi'thetruni involved. 

 By Heebeet Campion. 



In an earlier volntne of the Ann. & Mag. Nat. Hist. (ser. 8, 

 vol. xiii. pp. 495-504 ; 1914) a number of cases were recorded 

 illustrating the exact nature of the food consumed by adult 

 dragonflies. More recently a series of observations on the 

 same subject has been made in Nyasaland by Dr. W. A. 

 Lamborn, while studying the bionomics of Glossina on 

 behalf of the Imperial Bureau of Entomology. These 

 observations were made at two points on the western shore 

 of Lake Nyasa, and an account of tliem was published in the 

 * Bulletin of Entomological Research/ vol. vi. p. 252 (1915). 

 The more northern locality — the Lingadzi River — was visited 

 in February 1915, and Monkey Bay, some 60 or 70 miles to 

 the south, in April and May of the same year. At each 

 locality the dragonflies most frequently seen to take prey 

 belonged to a single species of Orthetriun, and, as is usual 

 ■with the African members of that genus, the determinations 

 have proved to be a matter of some difficulty. The two 

 species in question resemble one another very closely, and I 

 can see nothing to separate them either in the form of the 

 abdomen and the female genitalia, or in the coloration of the 

 pterostigma, membranule, and the base of the hind wing. 

 They may be distinguished, however, by certain differences 

 in the male genitalia, and, taking these as the criterion, I call 

 the series from the Lingadzi River Orthetruni brachiale, 

 P. de B., while to the series from Monkey Bay I apply the 

 name 0. chrysostigma^ Burm. 



The shape of the hamule in the male is sufficiently constant 

 for immediate recognition throughout each of the two collec- 

 tions. The Monkey Bay series has the form ligured by 

 Dr. F. Ris for chrysostigma (Coll. Selys, Libelh fasc. x. 

 p. 206; 1909). That form seems to be the common one for 

 the species, but I have seen specimens from West Africa which 

 show that the hamule is subject to a certain amount of varia- 

 tion in this as in otlier species of the genus. It may be said, 

 in passing, that the species here called chrysostigma, and 

 figured by Ris under that name, is somewhat different in the 

 form of the hamule from the type-material from Teneriffe. 

 The difference will be appreciated -when comj)arison is made 

 with Calvert's figure of the genitalia of Buiineister^s ])aratype 

 (Trans. Amer. Ent. Soc. xxv. pi. i. fig. 11 ; 1898), in whicli 

 the anterior branch of the hanmle is represented us being 

 "without any hook at tip, straight, blunt" [loc. cit. p. 86). 



