( -^cl ) 



ibnnulatetl by biologists, the case of Paclii/Ua darceta Ijecomes of general 

 imijortauce, counselling caution, since darreta has the right harpe more reduced, 

 and hence proves either that there is no inherited tendency in tlie Seminae to 

 a left-sided reduction, or, if there is, that the opposite development has taken 

 place in spite of that tendency. It may be a matter of little moment to an 

 outsider that the only species in tlie second division of the Sphingidae which 

 has in the ])upa a projecting tongue-case, as it is found in many Aclierontiinae, 

 is Rlii/Hchol'tba actcus ; but the matter becomes ditferent if we explain that, 

 firstly, the presence of a free tongue-case in RIn/ncholaba and Aclierontiinae is 

 not a sign of relationship, as the organisation of tiie insects proves, and lience 

 demonstrates the ])0ssibiIity of the appearance of a similar conspicuous character 

 in very distantly related groups, and, secondly, that tlie similarity again cannot 

 be mimetic, since the pupae are buried. 



In chemistry and physics minute research discloses tlie secrets of Nature. 

 In biological sciences minuteness of research is as much rec^uired as there, if 

 we wish to understand the phenomena of life. Systematic work can do much 

 towards that end ; it is the only means of checking off, proving and disproving, 

 generalisations. But to serve as a reliable censor of conclusions, the observa- 

 tions must be exact, and therefore minute, since exactness cannot be attained 

 without minuteness of imjuiry. A simplification of systematic research by 

 narrowing it down, as advocated in certain quarters, to tbe solution of the 

 questions " obvious ditference or no obvious difference, hence species or no 

 sjiecies, genus or no genus," takes the life out of it. But if tiiese questions 

 are made subordinate, and therefore systematic work suliservient, to the liigher 

 issues of biolugy, the dry detail of distinguishing characters and the ajiparently 

 futile labours of the de^ciiber of species and other classificatory units become 

 iill-iniportant in the science of life, as sui)|>lying sound criteria, where otherwise 

 a lively imagination might run wild and substitute plausible a>sinuj)tioiis for 

 facts. Looking from this point of view at the iliagnosrs of the genera and 

 species of iSjiIiinyii/ue it will be found that they are a soiu'ce for information of 

 a general character. 



If we compare the pedigrees (facing pp. 24, 499, etc.), with one another, and the 

 characters there mentioned with the fuller descriptions given in the body of 

 the Revision, the first tiling which strikes one is the frequent repetition and 

 reappearance of the same diagnostic character (for instance, the absence of a 

 jinivillns, or tiie spiuosity of tlie tiliiuc). AVhetiier our classification is accepted 

 us valid or not, the fact remains that there is very frequcintly a close agreement 

 in one or more characters between sjiecies and genera of near or of distant 

 relationshij) in the Hawk Moths, an agreement wliicli renders the classification 

 of the 'Spliinyidae esjiecialiy difficult. Since the agreement refers to many details 

 of many organs, as well as to the colour and structure of the scaling and the 

 shape of the body and wings — which give the insect its habitus — the Sp/n/u/idae 

 furnish indeed an abundance of material for a Study of Similarity, towards 

 which we ofter a few remarks. 



