16 Mr. Westwood's Observations on the Genus Derbe. 



EXPLANATION OF THE PLATES. 



N.B. The same letters and marks are used throughout the figures to indicate such of the 

 veins of the different wings as I consider to be the analogous representatives of each other. 



Tab. I. 



Fig. 1. Derbe semistriata, Westw. 



A. The head with the frontal carinas and antennae seen from above and in front. 



B. The head seen sideways. 



C. The same seen from beneath. 



D. The fore-wing. a. The mediastinal vein. b. The postcostal vein. r. The median 



vein. d. The anal vein. o. The representative of the outer brunch o of the 

 median vein of Mysidia. q. The small transverse vein connecting the post- 

 costal and median veins, here forming, with o, a branch of the postcostal vein, 

 the veins between o and oo being branches from this vein. The shaded part. 

 x, represents the supplemental part of the wing not found in Mysidia. 



E. The hind- wing. 



Fig. 2. Derbe strigipennis, Westw. 



A. A part of the right fore-wing, showing the regularity of the branches t o and *. 



B. The left fore-wing, with the same branches similarly marked. 



C. The hind-wing. 



Fig. 3. Mysidia albipennis, Westw. 



A. The fore-wing, with the principal veins marked as above, b* Terminal branches 



of the postcostal vein. ,. The situation where the portion of the wing shaded 

 in Fig. 1 D. is omitted in Mysidia. 



B. The hind-wing. *. The postcostal vein, simply bifid at the tip. 



Fig. 4. Mysidia lactifiora, Westw. 



A. The fore-wing „. The terminal bmich rf ^ ^.^ ^^ ^ ^ 



precede branch of the same vein by the short branchy but also at the same 

 fame so connected with the postcostal vein by the shorter branch g, as to .ppe« 



rather as a branch of the ,atter than the former. ,. The base „f the L 1 



branch of the median vein. 



B. The hind-wing. 



C. Head seen sideways. 



