440 THE BL'TTEllFLIES OF NEW ENCiLAXD. 



and America is due altogether to their boreal character ; that their occur- 

 rence on the two continents, looked at from a broad [)oint of" view, must 

 be regarded as the consequence of a continuity or close proximity of land 

 during later tertiary times when a warm climate prcAailed in the high 

 north : and that the distinction between them, and even the representation 

 of the same genus on the two continents by clearly different species, is due 

 to the subsequent separation of the two regions in glacial and post glacial 

 times, and the variations which isolation, a difference of climatic condi- 

 tions, and their general environment have brouglit al)out in the la[)se of 

 time. 



BIBLIOCiUAPHV. 



Tlio literature iipuu thi>^ siihjeet is largely polemical, very scattered, and generally brief. 

 Walsh published in 1864 in the Proceedings of the Entomological society of Philadelphia a list 

 of butterflies said to be common to North America and the Old World ; Mosichler has considered 

 The matter in his papers on the Lepidoptera of Laln-ador, mostly in the Stettiner entomologische 

 zeitung; Zeller in his review of Edwards's Butterflies, and various papers by Speyer and 

 Moschler in the same journal also discuss it. See also my comparison of the butterfly faunas of 

 Europe and America in the Proceedings of tlie American associatioji for 1870. 



Table of species of Vanessa, based ox the e(j(j. 



Vertical ribs less than twelve in number (Fi/rcmeis) atalanta. 



Vertical ribs more than twelve in numl)er {Neopyrameis). 



Egg not more than one-tenth higher than broad hiiiitera. 



Egg al)out one-third higher than broad .cardui. 



Table of species, based on the caterpillar at birt/i. 



Upper hairs of bod\' nearly straight, hardly more than half as long as width of head 



{Pyrameis) atalanta. 



Upper hairs of body considerably curved, about three-fourths as long as width of head (Keopy- 

 rameis). 



Body highly variegatetl huntera. 



Body of nearly uniform tint : cardui. 



'Table of species, based on the mature caterpillar. 



Lighter markings in front of supralateral spines consisting of conspicuous round spots 



huntera. 

 Lighter markings in front of supralateral spines consisting of slender, inconspicuous, longitu* 

 dinal streaks, 

 Spiiudes of apical circlet as long (not including the terminal thorn) as the spine below the 



circlet cardui. 



Spinules of apical circlet not one-third so long (not including the terminalithorn) as the 

 siune below the circlet atalanta. 



Table of species, based on the chrysalis, 



A distinct supralateral tubercle on either side of the eighth abdominal segment. 



.Supralateral tulK>rcles bluntly conical huntera, 



Supralateral tubercles sharjily eonicid atalanta. 



No distinct supralateral tulx-rcle f)n eighth altdominal segment cardui. 



