Materials, Theie Taxonomy and Natural History 39 



The species L. muUitcBniata Stal (habitudinal variant multitwniata Stal, 

 recurrent mutant melanothorax Stal; saltation tacubayensis; biotype multi- 

 twniata Stal ; habitudinal variant variabilis nov. var. ; habitudinal variant inter- 

 media n. var., recurrent mutant melanothorax Stal), L. oblongata n. sp. (bio- 

 types, (a) red, (6) orange, (c) yellow), L. rubicunda n. sp., L. decemlvneata 

 Say (saltations pallida n. var., defectopunctata n. var., minuta n. var., tortuosa 

 n. var., melanieum n. var., rubrivittata n. var.) represent a group entirely con- 

 fined to the temperate and cold uplands of Mexico and the plains and prairies 

 of the United States and Canada, as shown in plate 5 — typically temperate or 

 upland savannah inhabitants, and all feed upon solanums related to 8. ros- 

 tratum, or 8. elceagnifolium or 8. tuberosum. 



The species L. juncta Guer. (habitudinal variant texana Sch.), L. dejecta 

 Stal, and L. tumamoca n. sp. represent a group divergent from the two above 

 groups and inhabiting portions of the Atlantic and Mexican Gulf Coastal Plain 

 and Pacific coast desert, as shown in plate 3, feeding upon annual and perennial 

 solanums of diverse kinds. 



That I may clearly establish the nature, quality, and source of my material, 

 I have gone fully into the taxonomic study of it, especially in the living animals, 

 their distribution, habits, and ecology, and in this paper I have presented the 

 essential facts known bearing upon these points. It will be necessary to repeat 

 some facts and data already in print, but completeness in the treatment of this 

 portion of the subject is essential at the present time. The diverse series of 

 experiments, to which various members of this group have been, are now being, 

 and will in the future probably be subjected, demands that no effort be spared in 

 ascertaining the uttermost information concerning the condition and relations 

 of the materials in nature. 



TAXONOMIC AND GENETIC DIVISIONS. 



At the outset of the study of this aspect of the problem I am confronted by 

 the question of what it is that constitutes a species; further, there are the 

 problems of the lesser units or divisions present in some of the species, and of the 

 orientation and terminology to be applied. 



In nature there exist only individuals, each with its genetic line of descent, 

 and the aggregation of these genetic lines into groups, and it is this latter aspect 

 of the problem that presents the greatest difficulties. The mere fact that a form 

 breeds true to itself is no criterion and no reason for considering it a species, 

 and were this basis adopted an almost infinite number of species are possible 

 even in one narrow group, depending upon the skill of manipulation and the 

 minuteness of the dififerentiating characters employed by the observer. 



In this investigation I am of necessity forced to consider and use species, and 

 I have from experience come to think of them as organic systems distinguished 

 by a limited array of qualities, which perpetuate themselves in nature, and are 

 separated by a distinct complex of qualities from other related species. Within 

 any such group there are potentialities present in the diverse qualities and their 

 permutation for the isolation, by genetic methods, of a varying number of pure- 

 breeding lines. Also, in some specific groups in one or more areas, the accentua- 

 tion or suppression of one or more of the qualities marks off the members in- 

 habiting that area into a geographic variety. So, too, there are occasional sports, 

 appearing one at a time and at irregular periods, and also regularly recurring 



