Grote.] *J^^ [Oct. 18, 



through inheritance or natural selection, influenced by its surroundings 

 and its habits, so that the larval difterences have been evolved by a 

 natural protective law. These views have been recently more fully 

 brought out by Mr. Dyar. The moths on the other hand have re- 

 mained of a more uniform gray color, copying to some extent the bark 

 of the trunks of the trees against which it is their habit to rest in the 

 daytime. Thus it was shown that the larva varied independently of 

 the moth, suiting itself to the very difterent conditions under which its 

 life was passed. I concluded, in 1876, that the immature stage of 

 growth has submitted independently to modification. I allude to these 

 observations now mainly to show how wonderfully these larval modi- 

 fications have been retained in the case of the American and European 

 representative species, and to draw attention to the possibility of ascer- 

 taining the oldest larval type in the genus, from which the others may 

 have been in time evolved. It would seem as though both protective 

 forms (Bisulcia) green like the leaves, and repellant forms (Jochesera) 

 occur in this same genus. The usual larval type of Apatela may now 

 be found perhaps in Pharetra, hairy, gayly colored and bristled, resem- 

 bling Arctia, or again with longer dorsal tufts (Trisena) recalling 

 JSTotolophus. A light fleecy covering of silky hair in Acronicta may, as 

 Mr. Dyar suggests, be protective ; it brings to mind the larva of 

 Sijilosoma. One of the most beautiful larvae is that of Apatela 

 aceiis, the type of the genus, with dorso-lateral tufts of fawn-colored 

 hair enclosing a series of bright markings on the back ; it is proba- 

 bly repellant. While Dr. Chapman's studies of the pupae give us thi'ee 

 principal types, it seems that more are aff'orded, both by the larval and 

 irnaginal forms of Apatela. A grouping from the imago alone will lead 

 to a different arrangement from that by the larva, or by the pupa. 

 Thus I prefer to increase the subgeneric divisions in this genus in the 

 eff"ort to fit our nomenclature to the facts. Certain of the groups show 

 a greater general correspondence between larva and perfect insect, that 

 is they contain a greater number of species generally agreeing in both 

 stages, these are Triaena and Pharetra. Whether in these groups the 

 species have been more recently separated, as suggested by Dr. Chap- 

 man, is a matter of doubt, but seems a reasonable suggestion. This 

 view would fall in with what I have suggested to have happened in 

 other cases, such as Hemileuca, Datana, Phalera. There would seem 

 to be no genus which ofl'ers a more interesting field to the biologist 

 for exploration, and the opening aff'orded by Dr. Chapman's work 

 will guide the student of our richer fauna to still more important 

 results, arising from his larger material. 



RoEMER Museum Hildesheim, October, 1895. 



