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VIII. A Monograph of the Lepidopterous Genus Castnia and some allied Groups. 

 By J. O. Westwood, M.A., F.Z.S., Sfc. 



(Plates XXVIII.-XXXIII.) 



Head June 17th, 1875. 



NOTWITHSTANDING the vast additions which have been made during the last 

 quarter of a century to the lists of species of Lepidopterous insects, especially by the 

 entomologists of our own country, the observation of Latreille, in his most valuable and 

 classical work the ' Genera Crustaceorum ' &c, vol. iv. p. 186 (" Lepidopterorum ordo 

 entomologorum scopulus : horum insectorum etenim instrumenta cibaria simplicia ; an- 

 tenna? pro sexu diversse; metamorphoses permultorum nobis ignotse; idcirco nepotes 

 nostri methodum optimum soli confident "), is almost as true now as it was when 

 written, seventy years ago. In fact, the circumstance of such great numbers of species, 

 for the most part of exotic origin, being added to the already numerous tribes of Butter- 

 flies and Moths, without, in the greater number of cases, any actual knowledge of their 

 transformations or special structure being furnished by the captors or describers, has only 

 tended to render that " still darker which was dark enough before." If, at the same 

 time, we turn to the generic distribution of these insects, we are bewildered by the 

 infinite number of new groups which have, as it appears to me, most unnecessarily been 

 introduced into the science, and the never-ending change in the employment of old 

 generic names. This has in a great degree resulted from an insufficient appreciation of 

 the relative value of the characters which constitute a species and the illogical raising 

 of such characters to a generic rank. Thus no sooner had I published a monograph of 

 the Australian species of sac-bearing Moths, for which I adopted the generic name of 

 Oiketicus, proposed by the Rev. Lansdown Guilding, in the ' Transactions of the Lin- 

 nean Society,' in which paper I described the varying structure of the antenna?, wing- 

 veins, and cases formed by the larvae, than my specific details were seized upon, and each 

 species erected into a genus, characterized from my figures. Again, we have seen in a 

 recent American publication some of the Swallow -tailed Butterflies, which had uni- 

 versally been considered a species of the old genus Papilio, separated off from the 

 rest, and formed into different genera ; whilst the old generic name Papilio has been 

 entirely removed from the family, and applied to one of the genera, or rather to one of 

 the species of the genus Vanessa — each of the other species of the latter group being also 

 raised to generic rank, whilst almost every species of North-American Hesperiidee has 

 been formed into a separate genus. If, again, we look at the general classification of the 

 Order in the hope of supplying the desideratum of a "methodus optima," to which 

 Latreille especially alluded in the paragraph quoted above, I fear we are but little further 

 advanced towards the attainment of that end than our forefathers. By the employment 



SECOND SEBIES. — ZOOIOGT, VOL, I. Y 



