62 



THE ENTOMOLOGIST S RECORD, 



A phylogenetic sketch of the Pyrameid group of Vanessids 



(^ivith plate). 

 By T. REUSS. 



While studying temperature forms I became convinced that the 

 reason why so many aberrations often looked so curious to one, lay 

 chiefly in the fact that the observer would always, in his mmd's eye, see 

 the fades of the type behind that of the aberration, simply becauseit came 

 natural to him to look upon an aberration as a dependent form, and 

 that, therefore, when for instance I had tried to grasp the facial details 

 of unfamiliar foreign species, l'i/ra»ieis iiujrinna, Doubl., and F. indica, 

 Herbst, by comparmg them mentally with those in the familiar 

 facies of P. canhd, L., and P. atalanta, L., I had unwittingly acknow- 

 ledged the existence of what might be called a facial interdependence 

 between the different species. This, if it could not mean that P. 

 myrinna was an aberration of 1'. cardui or P. atalanta, certainly 

 pointed out that these different species of to-day had radiated from a 

 common ancestor, beginning as aberrations, local (climatic) or seasonal 

 varieties of the central form, for, just as aberrations, budding round a 

 central type, still facially betray their common origin, so also might 

 a group of different species, thought of as ramifications from one 

 central palfeentomological form (generic ancestor), be expected to show 

 signs of their common origin by an interdependence in facies. Of 

 demonstrative material in this sense, those of the Vanessids, usually 

 grouped under the generic name Pyrameis, offer perhaps some of the 

 best by reason of their daintily elaborate markings ; and the aberra- 

 tions that are available of P. cardui and I', atalanta, as also the 

 veritable encyclopaedia of " family likenesses " exhibited (in the field !) 

 by Araschnia levana-prorsa with its intermediate forms, tender 

 excellent material for checking the value of the evidence found in the 

 facies of the Pyrameids themselves. In the accompanying plate (vol. 

 xxii., pi. i) I have tried to depict some of these forms in " black and 

 white," purposing to show the details of the patterns free from the 

 differentiating element of colour. 



These Pyrameids, which include species of world-wide distribu- 

 tion, as well as species which are of comparatively (or even extremely) 

 local occurrence, illustrate strikingly that the experimentally 

 ascertained climatic influence* of light and temperature on the facies 

 of butterflies, figures as the chief factor of facial change, that, indeed, 

 when the efforts of this factor are obliterated by the habits of a species, 

 then that species will remain facially comparatively constant all the 

 world overt . 



* To be exact, the power of climatic influence was discovered by the natural 

 example of .-1. levana-prorsa (the first publication on the subject being by Dorfmeis- 

 ter, 1864), and was afterwards experimentally corroborated. 



t Before proceeding, a short sketch of the Pyrameid species giving a general 

 oversight in the sense implied, would help to simplify my text. As is well-known, 

 only two Pyrameids, Fyrameis cardui and P. atalanta, occur in the British Isles ; 

 both come as regular immigrants from the south. In appearance the two species 

 are extremely unlike each other, at least to a casual observer. Now, looking on 

 the Pyrameids of the world, the first thing that strikes one is that the several forms 

 are divided by their facial appearance into two apparently well-defined groups of 

 six or seven species each, in one of which the constituent species all remind one 

 facially of the familiar P. cardui, and in the other they all resemble P. atalanta, 

 much in the same way as aberrations resemble their types. For the sake of con- 



