302 Descriptions of JSFeiv JVoctuce, etc. 



With regard also to the differences in larval color and 

 ornamentation in these representative species of Nbctuce, we 

 find that they are often more clearly expressed than in the 

 perfect state. This immature stage of growth has submitted 

 independently to modification. An instance is offered by 

 the American Apatela occidental is and the European Apatela 

 psi. Here the moths are exceedingly similar, and difficult 

 to distinguish ; while the larva of the American species, de- 

 scribed by Mr. Wm. Saunders, of London, Ontario, offers 

 prominent differences when compared with this same state in 

 the European species. All the cases cited by Guenee, based 

 upon drawings of the larvae of North American JSToctuce, by 

 Abbot, where the moth resembles an European form very 

 nearly, but the larva is very different, should probably be 

 considered here. The larva has varied through natural 

 selection, while the perfect form has remained more fixed. 

 The whole extensive genus Apatela ( — Acronycta) is re- 

 markable for the eccentricities of the larval forms as com- 

 pared with the uniformity of the species ; so that the conclu- 

 sion is not unreasonable that these larval differences have 

 been evolved by a natural protective law.* There is within 

 the genus Apatela another case of representation, between 

 the American Apatela funeralis and the European Apatela 

 alni, where a very singular form of larval ornamentation has 

 been equally retained, while the comparisons as yet made 

 between the moths show sufficient difference to warrant dis- 

 tinctional names. Again, in the case of the larvae of the 

 Cotton Worm moth (Aleda argillacea) I have pointed out 

 two varieties,! which feed side by side, one with and one 

 without a dorsal stripe. It will be interesting to observe 

 the particulars of the struggle between these two varieties in 

 the case of this imported insect. 



Where the habit of life of the larva leads to no conceal- 



* Bull. Buff. Soc. Nat. So., 1, 130, quoted by Prof. Morse in his Address before the 

 Section of Biology of the Am. Asso. Adv. Sci., Buffalo, 1&76. 

 t Alabama Geological Survey for 1S75, 201. 



