6 PROCEEDmGS OF THE NATIONAL MUSEUM vol. ic« 



An outstanding characteristic of the genus is the presence of a small, 

 very thin, triangular tooth (referred to as process A) near the end of 

 the telopodite. All of the subspecies of pela are provided with this 

 feature. In most of them there is also an expansion of the end of the 

 telopodite and a supplementary oblong lobe, or process (referred to as 

 process B). In the case of dactylifera, process B has become un- 

 usually enlarged, and A has disappeared entirely. In this instance, 

 and also in those subspecies of pda where B is enlarged, it is useful 

 to distinguish the true ending of the telopodite with the term solenom- 

 erite (S). Possibly the name parsolenomerite might be adopted to 

 replace "process B," but I hesitate to devise a terminology until 

 homologies have been worked out for all the genera of the family. 



One may observe some geographic variation in the gonopods of the 

 forms of Dixiora pela. There is a trend from south (pela) to north 

 {jowleri) toward increase in the size of the prefemoral process and a 

 corresponding decrease in the length and arch of the telopodite blade. 

 A similar variation occurs, altitudinallj^, in a reverse direction in that 

 coronata (presumably a montane derivative oi Jowleri) shows tenden- 

 cies back toward the characters of pela. 



The average size of series varies considerably and at first suggested 

 itself as a secondary taxonomic difference. However, this varies 

 witliin subspecies as well as between them, and I conclude that 

 dimension is a character which varies at least with the individual and 

 at most with any given micropopulation. It may be only a reflection 

 of propitious environmental conditions. 



Various other characters, such as the shape of the paranota of the 

 caudalmost segments, were considered for their possible utility in 

 separating subspecies. Several variations, which at first appeared to 

 be useful, were found to break down when series of specimens were 

 checked, and in general it seems that such qualitative differences, even 

 if stable, are so slight that they would be negated by the normal 

 amount of error inherent in making drawings under low magnification. 



Genus Dixioria Chamberlin 



Dixoria Chamberlin, Proc. Acad. Nat. Sci. Philadelphia, vol. 99, p. 28, 1947. 

 Deltotaria (not Causey) Hoffman, Proc. U. S. Nat. Mus., vol. 99, p. 379 (in part), 

 1949. 



Type species: Dixioria dentifer Chamberlin 1947 (=Fontaria pela 

 Chamberlin 1918), by original designation. 



Diagnosis: A fontariid genus characterized as follows: prefemora 

 of legs with a sharp distal spine, coxae with or without small ventral 

 spines; sternites witliout obvious processes at bases of legs and not 

 produced on caudal margin; tergites smooth, paranota rather small, 



