314 THE CANADIAN ENTOMOLOGIST. 



CALLOSAMIA ANGULIFERA. 



BY A. RADCLIFFE GROTE, HILDESHEIM, GERMANY. 



Through the great kindness of a friend, I have received cocoons of 

 Callosamia angulifera. These are stemless, and at once distinguishable 

 from those of C. promethea. This character bears out the theory (see 

 Can. Ent. for April, p. 94) that C. angulifera is the older, more 

 generalized form in the genus. In my work on the Saturnians, June, 

 1896, I tried to show that the stemmed cocoons of Philosamia, Attacus 

 and C. promethea were specializations and a more modern development, 

 and gave probable reasons for the acquirement of the habit of fixing the 

 cocoon to the branches, so that it might not fall with the leaf in the 

 autumn (1. c, pp. 15-16; also Plate I.). I have shown that, in a general 

 way, the specialization of the Attacid cocoon keeps pace with the 

 specialization of the imago in the whole group. Hut these specializations 

 do nor move exactly together, and the independence of the different 

 stages in this respect is decidedly indicated. In the case of C. promethea, 

 the male has evidently more recently become black, while the cocoon has 

 added the stem wanting in the supposed primitive form : C. angulifera. 

 But Samia shows no disposition in this direction, and yet the imago must 

 be considered more specialized as compared with Callosamia. The 

 specializations are unequal throughout, not only as between the different 

 stages of larva, chrysalis and perfect insect, but development is hastened 

 or retarded in different parts or organs in the same stage. Until this is 

 appreciated, judgment will constantly be at fault in classifying these 

 insects. The characters upon which genera are founded are those 

 of comparative specialization. 



In the passage of Samia to Rothschildia, the tendency to form a 

 stem to the cocoon becomes apparent, evidently controlled by the nature 

 of the food-plant. I have suggested (1. c ) that this habit of fixing 

 the cocoon to the tree by an artificial stem spun round the leaf and 

 fastened to the twig above, is correlated with the increase of the wings in 

 surface dimension. My studies on the species of Samia are not 

 concluded. So far it appears not improbable that the Eastern forms, 

 Co'umbia, Gloveri, Cecropia, are developments of the Western 

 Ca lifo rn ica ( Ceanoth i) . 



