1S1I6.] 83 



Dr. Seidlitz [Naturg. Ins. Deutschl., v, p. 583 (1894)] adopts the 

 name Triholium navale for the species ; but, as I have shown above, it 

 is more than doubtful if the description of the New Zealand insect 

 was made from a specimen of the so-called T.ferrugineum. 



Horsell, Woking : 



March 1th, 1896. 



SINGULAR MONSTROSITY IN A DRAGON-FLY. 



BY ROBERT McLACHLAN, F.R.S., &c. 



Early one dark morning last week I was occupied in preparing some 

 Dragon-flies recently received from Venezuela, and which had been 

 placed in the relaxing box in the original papers. One Hetcerina ^ 

 {fl. occisa, Hag.) was apparently very intractable, as I could not 

 induce the four wings to resolve themselves into pairs on the setting 

 board. At first 1 attributed this to one wing on the right hand side 

 having become crossed over to the left (a not uncommon kind of ex- 

 perience in setting dragon-flies sent in paper envelopes, and often due 

 to the pin being badh' inserted). At length the insect was removed 

 from the board, and an examination revealed a very singular instance 

 of monstrosity, which accounted for the intractability. On the left 

 side are three wings, two mesothoracic and the other metathoracic. On 

 the right side only one wing, and that metathoracic ; the muscular wing- 

 attachments on the mesothorax are present, but with no rudiments of 

 the wing itself. The insertion of the supplementary anterior wing on 

 the left side is at a point almost immediately beneath, and slightly 

 inferior to, that of the normal wing. The normal anterior and pos- 

 terior wings on the left side, and the posterior on the right, are those 

 of a fully mature individual, the red pigment being highly developed. 

 The supplementar}^ anterior wing on the left side is nearly normal in 

 shape and neuration (the only appreciable difference being that the 

 inner margin is slightly more excised at the base), but the pigment is 

 not developed, the wing in that respect being similar to those of very 

 immature examples. 



Cases of monstrosity in Dragon-flies are extremely rare, and it is 

 advisable to put all such on record when met with. Having regard to 

 the future, it may be well to explain that in my preliminary endeavours 

 to induce the wings to accommodate themselves to the usual position on 

 the setting board, the normal left anterior wing became loosend at its 

 attachments, and had to be secured by liquid glue. 



Lewisham, London : 



Marih Zrd, 1896. 



