SIDELIGHTS ON THE LEPIDOPTEEOLOGICAL WORK OF THE CENTURY. 35 



many others of less importance. The answers to these questions are of 

 the most profound importance to man in their social and political 

 teaching, as regards his own race, and are valuable, but much less so, 

 as regards his domestic plants and animals, and indeed all organic 

 nature with which he is constantly in contact. The hoped-for results 

 can be reached much more rapidly in dealing with insects with an 

 annual periodicity than by experiments on higher animals of a much 

 longer and more complicated existence. 



The enormous increase in our knowledge of the earlier stages in the 

 lepidoptera is perhaps a notable feature of the century's work. If we 

 confine ourselves to the pal^earctic fauna, it has far exceeded the growth 

 of the number of known species, but if we include exotic species where 

 much less has been done, it may be doubtful whether we knoAV the 

 earlier history of a larger proportion of recorded species than we did 

 at the beginning of the century. Nor must we forget that much 

 excellent work was then already done, a list of the authors up to 1800 

 would indeed be a long one. Though not the earliest, Swammerdam 

 and Keaumur stand out as landmarks at the end of the 17th and 

 beginning of the 18th centuries, nor should we forget the work of 

 Madame M. S. Merian at the same early date, not only amongst 

 European but also tropical insects. The work of Roesel and Sepp 

 at the end of last century, on the life-histories of lepidoptera, is as 

 excellent as any to be found until we reach quite the end of the 19th. 

 As regards larva^, we must go to America for our present standpoint. 

 The careful descriptions of Packard, Scudder, Dyar, and others, of the 

 larvje at all stages, from hatching onwards, omitting no feature and 

 especially noting the structure and distribution of the tubercles, has 

 led to Dyar formulating a clear scheme of the evolution of the tubercles, 

 both as to their positions and armatures. Granting this may want 

 further elaboration and even correction, it is an immense advance. I 

 might mention that though the work of Buckler and Hellins gives no 

 indication that they attached any special importance to such details 

 as the tubercles, Mr. Hellins, toAvards the end of his career, was much 

 impressed with the idea that a close attention to the character and 

 disposition of the tubercles would afford useful clues to relationships of 

 larvJB and families of lepidoptera, and wished he had attended to them 

 in his earlier work ; this subject is more than once referred to in my 

 corespondence with him. Hellins was, I think, the only Englishman 

 who got even so far, before Dyar showed us where we ought to be. 



It is a feature of quite the end of the century to prepare mono- 

 graphs of the morphology of special parts and organs throughout 

 larger and smaller groups. As careful and elaborate treatises one may 

 refer to Renter's on the " Palpi of Rhopalocera " and Dr. Karl 

 Jordan's on the " Antenna; of butterflies." Dr. Dixey's work on the 

 Pieridae and other butterflies best classifies itself here. The earliest 

 work of this character is probably that on the male genital appendages, 

 and the use made of these by M'Lachlan in his great work on the 

 European trichoptera, an order in which they are, fortunately, more 

 easily examined than in the lepidoptera, is perhaps the earliest instance 

 of their being fully examined throughout a large group of species, and 

 of their immense value in distinguishing species. In the same work 

 the neuration of the order is examined with equal completeness, and 

 its value similarly demonstrated. In neither of these matters was 



