THE REVISION OF THE SPHINGIDES. / 



species. We fully understand what they mean here, but they leave 

 us without any definite criterion as to when forms come under the 

 one or other of the declarations we have just placed together. They 

 probably mean — but we should have liked them to have said — that it 

 is but rarely that any decisive criterion can be applied, and that 

 analogy only can decide, and the application of this may reasonably 

 differ in the hands of different authorities whose education and 

 experience have been amongst different sets of species. 



In the remarks on genera and higher categories we may quote : — 

 " To define genera and higher units is not always an easy matter. In 

 order to render a definition precise, a close study is necessary of the 

 forms which come under the unit defined, as well as of the forms of 

 the allied units. The difficulties encountered have induced many 

 authors, especially in ornithology and entomology, to propose names 

 in genera, subfamilies, and families without attempting a definition. 

 The naked names thus introduced are a fit testhnonuon paupertatis for 

 their authors." " It has been our special endeavour to give a solid 

 foundation to the genera, supplementing and rectifying the vague and 

 faulty definition with which the workers in this group have contented 

 themselves." " We have laid special stress upon the genera conceived 

 by us, representing stages in the evolution of the Spldni/idae." 



The next section of the Introduction deals with the " Morphology of 

 Sphingidae," running to over 50 pages. Much of this is of the nature 

 of a summary, of which the details are to be found in the systematic 

 portion of the work. It is the wealth of detail here accumulated in regard 

 to the structure and anatomy of all the outer portions of the Sphingid 

 imago, that marks this revision as something definitely beyond anything 

 of the sort on the same scale that we have yet had on any family of 

 lepidoptera. The care and minuteness, as M'ell as accuracy of the obser- 

 vations, and the large number of species to which they relate, enforce 

 one's admiration. This is difficult to illustrate without unduly long 

 quotations. We may, however, refer to their most valuable observa- 

 tions on the labial palpi. " A character of the greatest importance m 

 the classification of the Hawk moths is found at the base of the first 

 segment. That is a patch of variable size of short (and doubtless 

 sensory) hairs, which is always present in one section of the family, 

 except a few reduced forms, and equally constantly absent from the 

 other section. The trustworthiness of the distinctive character was 

 discovered after we had separated the Achenmtiinae { = Acherontiicac -\- 

 Sphingicae -{- Spldwiidicae) and Aiiibidicinac from the rest of the family on 

 other grounds. This basal patch was found in butterflies and treated 

 upon at some length by Renter. It is of wide occurrence in moths." 

 To mention all the subjects dealt with would be to give a catalogue 

 of the parts of the external skeleton of Sphinges. " The singularly 

 meagre success attained in the definition of genera of Sphuujidae by the 

 authors of the old school — meagre even from their point of view — was 

 mainly due to the wings seldom offering in the neuration such obvious 

 distinctions as are found in other families of lepidoptera." 



The genital armature is described, not merely of the males, but 

 also of the females. "The sexual apparatus is of great taxonomic 

 value .... In a number of cases the apparatus is the only safe 

 guide in the recognition of species. From this point of view the 



