50 MEMOIRS OF THE NATIONAL ACADEMY OF SPIENCES. 



The distribution of most of the genera and nearly each species of Notodontians is shown ou 

 the nine phiin maps accompanying this memoir. It is believed that by having a number in con- 

 spicuous type, representing a distinct species, the map will both show at a glance the known 

 localities where they were found and also the distribution. When the entire group has been 

 discussed, we liope to present a final colored map showing the general distribution of insect life 

 in North America. 



SEASONAL VARIATION. 



Almost nothing has been done on this subject, except for the butterflies by Jlr. W. II. 

 Edwards, whose able investigations are well known. The only facts known as regards the 

 Bombyces are those stated to us by Mr. Beuteumiiller, who, in breeding Ichthyttra apicali.s, has 

 found that the sulniner and winter broods of this species are different in hue, the pale individuals 

 belonging to the summer brood and the darker ones to the earlier winter brood. 



Wc' have also called attention to the cases of Drcpdna urcuata and Dryopieris rosea, first 

 noticed by the late S. Lowell Elliot. Mrs. Slossou tells us that in Franconia, N. H., the early May 

 brood of the Geometrid moth, Seleiiea kentaria, is darker and richer in hue than those of the later 

 or summer brood. 



CLIMATIC VARIATION IN THE NOTODONTID^T:. 



In an essay on the general subject of climatic variation in our Monograph of Geometrid 

 Moths (pp. 584—589) we called attention to the changes in the size of the body, in the shape of the 

 wings, and in the coloration, observed in Colorado and on the Pacific Coast, in individuals of 

 species ranging across the continent. We gave a list of 27 species of Geometrid moths which 

 attain a larger size as we go west, and wliich in some cases have longer, more pointed wings than 

 individuals from the Atlantic Coast. 



Our observations on individuals of the present family- have been very scanty from the lack of 

 material, none of the collections I have been able to consult being rich in number of individuals; 

 also from deficiency on the labels of exact localities, and of information as to whether captui'es 

 were made on the plains or among the mountains in a State like Colorado, and whatever is 

 stated here should be regarded as merely tentative and suggestive, rather than final and 

 couclusive. 



Notodontifhv which attain a larger size in the Campestrian suliprovimr, includiii;/ lite I'acijic Coast, 

 than in the Atlantic or Appalachian and Austroriparian subprorinces. 



Ichthyura inornata. Schizura unicornis var. conspecta. 



Pheosia dimidiata. Cerura ciuera and var. cineroides. 



Species ichich have longer icings in the Campestrian suhprovinccs than in the Appnlachian and 



Austroriparian. 

 Schizura concinna (salicis). Cerura nivea. 



Species which tend to bleach out or to become paler than eastern imliridnals, and to lose their dark 

 markings in the Arid or Campestrian subprovinces {including the lowlands of California). 



Gluphisia wrightii. Ichthyura apicalis. 



var. astori;t. 

 severa. 



var. formosa. Scliizura unicornis. 



var. conspecta. 

 var. albofascia (Utah), Cerura cinerea. 



and var. nivea. 



It is not improbable that the Campestrian (Colorado and Utah) species of Ghiphisia, such as 

 G. ridenda, G. rupta and albofascia are climatic varieties of 0. septentrionis. 



' Proc. Bo8t. Soc. Nat. Hist., xxiv, p. 491, 1800. 



