262 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 112 



In recent years several opponents of the subspecies category have, 

 most correctly, pointed out that many workers have erected subspecies 

 on the basis of a single character in a limited region, without con- 

 sideration of the total variability within the entire species involved. 

 In such cases, whenever another (and perhaps equally important) 

 character is emphasized as the basis for separation, an entirely differ- 

 ent pattern of "subspecies" emerges. The present work has been 

 done in complete cognizance and appreciation of such circumstances, 

 but although all the populations in the genus Cherokia are held to be 

 conspecific, three of them appear to be so distinctive and so constant 

 throughout their ranges that recognition as subspecies seems to be 

 warranted and actually desireable. Those who wish to discard 

 trinomials may refer to latassa as the Cumberland Plateau population, 

 to georgiana as the Georgia population, and to ducilla as the Great 

 Smokies population, of Cherokia georgiana, but I do not see what is 

 to be gained by the substitution of polynomial vernacular names in 

 place of short Latin designations carrying the same implication. 



Summary 



A number of local populations within the genus Cherokia have been 

 given specific names in the past, in many cases the diagnostic charac- 

 ters being more apparent than real. A restudy of the genus, based 

 upon more than 400 specimens and typical material of most of the 

 names, shows that most of these species are merely local populations 

 of one variable species. The gonopods are remarkably similar in 

 all the material examined, and the external body form is equally vari- 

 able. It is concluded that the most extreme variants in the genus are 

 eventually connected by intergradient populations, and that Cherokia 

 is mono ty pic. 



The importance of this conclusion rests in its presumable effect on 

 the definition of species in the family Xystodesmidae. Common 

 practice of the past decade has resulted in the erection of numerous 

 specific names for millipeds from single localities, differing solely in 

 color pattern or other minor features. Such forms have been 

 apparently proposed in a sort of taxonomic vacuum which presupposed 

 that any difference must be of specific value. One paper (Causey, 

 1951), attempted to justify such an approach with the philosophical 

 suggestion that in some genera, specific differences obtain only in 

 nonsexual features, with the gonopods remaining identical or nearly 

 so in the different forms. Such species were designated by the special 

 term "isogenitive." 



It must be obvious that the validity of the idea of "isogenitive 

 species" rests entirely upon what was never proved, that the named 

 forms involved are actually different species. Presumably, as long 



