200 



pean si)ecies. For the origin of other species we shall have to go 

 backwards to the Plistocene and consider the identical species as 

 belonging to a former Arctogaeal fanna. The action of the steady 

 increase of cold which characterized the gradual inauguration of 

 the Ice Period would have been to drive the insects southward and 

 mix the Arctogaeal with the then existing "indigenous" southern 

 species. The summers of the middle Glacial Epoch probably af- 

 forded no opportunity for the existence of Noctuidae throughout 

 the Northern States. On the decline of the Glacial Epoch and with 

 a steady increase of warmth (still continuing) the species would pro- 

 gress northward again. We may regard such a species as Fidonia 

 Umitaria G. & R., found in Texas, as an outlying colony of F. fas- 

 ciolaria forced southward and retained by local influences, and 

 possibly having submitted to the modification which enables us at 

 this day to separate the two forms. During the Pliocene the com- 

 mon ancestor of the two forms may have been different from either. 

 During the Plistocene, Holocene and Eecent Periods, we must con- 

 sider such species as Hadena ai'cUca to have preserved their identity, 

 while many may have perished or submitted to modifications and 

 these latter may be represented by the closely allied species of the 

 two faunae. The Glacial Epoch may then supercede the " Atlantis" 

 of those Entomologists who looked for a geographical connection in 

 former times to account for the existence of identical or represent- 

 ative species on the two continents.* 



* I append here the description of a new North American Perigea ; 

 Perigea luxa n. s. 



S ¥ . — The male antennae are simple, pubescent beneath. Eyes naked, with lashes. Tibia 

 unarmed. Abdomen carinated, with extremely minute tuftlets. The glossy fore wings are 

 strongly widened outwardly, being narrow at base. The ornamentation is like that of Perigea 

 xanthloides^ but the color totally different and the size larger— blackish mixed with dirty ochery, 

 giving the primary a mottled appearance. The lines are geminate, black, filled in with ochery, 

 ill defined, waved or dentated. Claviform suffused with deep black, vague, subquadrate in out- 

 line. Orbicular ochery, moderate, ringed incompletely with black, with blackish center. Ren- 

 iform very large, somewhat 8-shaped, being medially constricted, colored like the orbicular, 

 with large internal black annulus. A series of white nervular points on the black subterminal 

 space beyond the dentate ochery shaded t. p. line. Subterminal line uneven, outlined by a suc- 

 ceeding ochery shading. Fringes dotted with ochery at the extremity of the veins. Hind 

 wings fuscous, a little paler at base, with pale, ocher-tinlcd fringes and without markings ; 

 beneath pale ochery, powdered with fuscous. Fore wings blackish except terminal space. 

 Hind wings pale with double fuscous shade lines and discal mark. Head and thorax mi.Ked 

 ocherous and blackish ; collar more ochery with black edging. Palpi as long as the front, 

 ' ascending, with well developed closely scaled terminal joint. 



Expanse, 32 m. m. New York (Mr. Meske) ; Alabama (Grote) ; Mass. (Mr. R. Tluixter). 



