298 



The following gradations in a regular series are, I think, established 

 from tlie above-mentioned facts : — First, Races exist having distinct 

 food-plants peculiar to each of them, but not, so far as known, 

 differing either in the larva or imago, (Clytus pictus.') Second, Ra- 

 ces exist having distinct food-plants, the larvse of which differ most 

 remarkablj'^ in coloration, but not in structure, and the Imagos are 

 almost and perhaps quite Identical, (^Datana ministra.') Third, There 

 exist what, accoi'dlng to the accepted laws of classification, we must 

 consider as distinct species, the larvae of which are structurally distinct, 

 and the cf imagos, to all appearance. Identical, though there Is every 

 reason to believe that the ? imagos, one of which is unknown, are 

 structurally distinct In the form of their antennae, (Sphingicampa dis- 

 tigma, n. sp. and Dryocampa bicolor Harris Walsh.) Fourth, There 

 exist what, according to the accepted laws of classification, we must 

 consider as distinct species, the larvae of which are structurally dis- 

 tinct, and the imagos, cf ?, to all appearance, identical, (Halesidota 

 tessellaris and Antiphola, n. sp.) Fifth, The great bulk of what we 

 call distinct species are distinct either in coloration, or In structure, or 

 in both, In both the cf ? Imago and the larva states. — It Is Impossible, 

 in my mind, to avoid arriving at the conclusion that these are but dif- 

 ferent stages in one and the same process, viz., the formation of a new 

 species. 



It is not necessary that those who believe In the origin of species by 

 hereditary descent should believe In any one exclusive method by 

 which those species are originated. Some, perhaps the great ma- 

 jority of species, may have been formed upon the Darwinian theory 

 of Natural Selection, some by changes in the conditions of life, and 

 especially by change of food, as in the above-recited cases, some by 

 what Prof Owen rather obscurely terms " the ordained potentiality of 

 second causes, from single-celled organisms, with innate capacities 

 of variation and development," (quoted In Silliman's Journal, Vol. 

 XXXVI., p. 298), and some by other yet unexjslalned processes. No 

 one cause appears to be sufficient to account for all the phenomena. 

 Natural Selection does not explain the origin of many structures, 

 both in the animal and vegetable kingdoms, which cannot be con- 

 ceived to subserve any utilitarian purpose, and " innate capacities of 

 variation " does not satisfactorily account for the many wonderful 

 coadaptatlons of structure met with in almost every organized being. 



LiMACODES SCAPHA Harris. Imago undescribed. ? Body ro- 

 bust, very pale chestnut-brown. Antennae more than attaining the 

 middle of the costa. Legs but moderately hairy, and of a very pale 

 chestnut-brown color. Wings very pale chestnut-brown, above and 

 beneath, the entire length of the costa of the front wing with a large, 

 velvety, chestnut-brown patch, beautifully regular in its shape, and 



