P K E F A C E. 



The subject of Yol. IV. of the ' Catalogue of Moths ' is the classifi- 

 cation of the Agrotino', consisting of about 12U0 known species and 

 constituting the first of the fifteen subfamilies into which the very 

 large and dominant family Noctuida', with some ton to twelve 

 thousand described species, is divided. 



The family has two main divisions — the Trifid group of subfamilies 

 with vein 5 of the hind wing obsolescent, inhabiting chiefiy the 

 temperate regions and with comparativel)^ few species in the tropical 

 and subtropical zones and those chiefly "found in mountainous 

 districts ; and the Quadrifid group with vein 5 of the hind wing 

 fully developed, very largely represented in the torrid zones 

 and with few species in the temperate regions and on mountain- 

 ranges. 



The difficulty of dealing with the Trifid group is greatly increased 

 by the great variability of many of the species and by the large 

 number of species described from Central Asia and JS'orth America, 

 tlie limits of variation and range of wliich are very imperfectly 

 known. 



In the Asiatic species Staudinger and Rebel's Catalogue has 

 l)ocn to a largo extent followed ; but some of the forms treated in 

 it as varieties will doubtless in the fulurc lie found to be distinct 

 species, and some treated as species will lie considered to be local 



