Mr. Westwood's Observations on the Genus Derbe. 7 



vein o, and to be connected with the outer branch of the median vein by a 

 branch p, which is but in fact the modified base of the branch o, supposing 

 that branch to be postcostal and not median. By adopting this view, we 

 should arrive at the conclusion that the branch o in Derbe semistriata is post- 

 costal, its true base being the short branch q, and that the other longitudinal 

 veins in the shaded part of the wing (1 D a?) are also postcostal. 

 The following species belong to the subgenus Mysidia. 



Derbe pallida, Fabr. (Perch^ron, Mag. de Zool. Ins., pi. 36). 

 D. squamigera, Fabr. ("Statura omnin6 praecedentis," Fabr.). 

 D. costalis, Fabr. ("Statura prsecedentium," Fabr.). 

 D. punctum, Fabr. 

 D. testacea, Fabr. 

 D. nivea, Fabr. 



I am in doubt respecting the three latter species, D.punctum being described 

 as having elongated wings, although it agrees with my species in colour, and 

 in having a black spot. D. testacea is described as of the "statura praeceden- 

 tis." D. nivea agrees with mine in having the wings " teneris niveis," but they 

 are immaculate. 



The two following species also belong to this subgenus. 



Mysidia albipennis. Westw. 

 Tab. I. Fig. 3. 

 Parva tenera; alis albis: anticis puncto parvo ante medium costse punctis 

 nonnuUis ad marginem internum venis transversis punctoque ante api- 

 cem nigris lunulis parvis fuscis marginalibus. 



Long. corp. lin. 2. Expans. alar. lin. 8. (mens. Angl.). 



Habitat apud Veram Crucem Americas ^quinoctialis. In Mus. Westw. 



Corpus totum albidum ; oculis lutescentibus ; antennis concoloribus. Collare album, macula 

 parva purpurea utrinque ad marginem anticum. Tegulce albae. Abdomen et genitalia 

 concoloria. Pedes etiam albidi ; tibiis anticis annulo fuscescenti ad basin alteroque ad 

 apicem. Ala tenerrimae, albae, pulverosse, translucidas, et parum iridescentes, venis pal- 

 lidis ; antica puncto nigro parvo rotundo ante medium costae ; vena parva transversa 

 (venara mediastinam et postcostalem conjungenti) ; basi ramorum duorum venae post- 



