MILLIPED GENUS CHEROKIA — HOFFMAN 231 



trast to the broad robust form occuring in north Georgia, as can be 

 seen from the accompanying photograph (see plate 1) of two speci- 

 mens typical of the extremes in this variable character. 



Determination of relative body width is by no means a precise 

 operation, yet by uniform measuring techniques the error is held to a 

 minimum. Naturally only well-preserved specimens can be used, 

 with the body lying flat and straight, and not noticeably telescoped. 

 In this position nearly all specimens have the first few segments a 

 little arched (due to the curling reflex) and the collum declined at an 

 angle of about 45 degrees. Efforts to reduce this arching usually 

 result in either breaking the specimen or unduly extending the front 

 end. Measurements have been made with vernier-scale calipers, 

 length to an accuracy of 0.5 mm. and width to 0.1 mm. The greatest 

 width normally occurs at the midbody segments but may be further 

 caudad. The width was in every case checked by moving the calipers 

 along the body until the widest segment was located. 



The simple ratio of width divided by length yields a value which 

 ranges from 19 to 28 percent. At any given locality from which a 

 series of measurements is available, the range of variation in this 

 ratio is not over 3 percent, and this magnitude is almost certainly due 

 to the errors inherent in measuring the length of preserved specimens. 

 Nonetheless, the mean value of the w/l ratio, plotted cartographi- 

 cally from as many samples as possible, produces an interesting sort 

 of distributional pattern. Figure 1 is a map reflecting geographic 

 variation in body form, the isophenes inclosing populations the mean 

 w/l ratio of which falls within the specified limits. 



From this map, it is seen that broad specimens with a ratio of 26 per- 

 cent or more occur over most of the generic range, chiefly but not 

 exclusively in low country. In the high ranges of the Great Smokj^- 

 Unaka Mountains the ratio is less than 24 percent, while populations 

 with intermediate values (24 to 26 percent) occupy a large part of 

 southwestern North Carolina in the Cowee, Nantahala, and Balsam 

 ranges. 



It has been found desirable to rely largely upon ratios derived from 

 male specimens, these generally being in greater supply and usually 

 easier to flatten and measure. A large number of females were stud- 

 ied, however, and these show a certain amount of sexual dimorphism 

 in being slightly wider at any given locality than the males, the w/l 

 ratio of the females being about 1 percent higher. 



Shape of paranota: Close examination of the lateral projections of 

 the metazonitcs shows the occurrence of two rather distinct forms. 

 In one of these forms (fig. 3,a), the paranotal scapulorae (new term, 

 from the Latin "scapula," a shoulder, and "ora," the rim of a shield) 

 as seen in dorsal aspect are strictly marginal; that is, they form the 



