ON THE CII1LOPODA OF NORTH AMERICA. 



21 



^ 



\ 



<r 





spines of the lower surface, of basal articulations of las! pair of legs, are more nume- 

 rous than in S. heros, and arranged in four rows instead of three. The difference in 

 arrangement is, perhaps, more apparent than real; the bomologue of the first row of 

 spines existing in some specimens of S. heros, but being placed a little higher up, 

 they are thrown with those on the inner side of the limb. The angular process has 

 fewer spines than in S. heros. Finally, a glance at the tables will show that, though 

 the species exist on common ground, yet that heros is a more tropical and 'polymorpha 

 a more boreal animal. 



Table showing the variations ■ ific characters. 



■ ii ns 6i longing la tht 



Aripc Trip. 



Fort Riley, Kansas. 



Fori Buchanan, Arizona. 

 Fort Riley, Kan- - 

 Fori M \ :is. 



Sonora and Chihuahua. 



9 



Fort Buchanan, Arzona. 

 Santa Fe. 

 ?Santa Cruz. 



Dr. T. II. Webb. 

 1 »r. i Irabatn. 

 Mr. Bravat. 



Dr. Irvin. 

 II. Brandt. 

 Capt. Plummer. 

 Major W. H. Emory. 

 1 



Dr. Irvin. 

 Mr. Howard. 

 Dr. Webb. 



r/nc. 29 



" 92 



- i 



-3 

 -3| 



3 



3J— 3 , : 



4 

 2J 



* The 



fraction 



tAre 



Locality undoubtedly mistaken. 



typical number of rows is four. The variations from this arc caused by some of the spines being a 

 of a line from their normal position ; they generally may be placed in four crooked rows, 

 the hinu legs with the anal appendages the original ones, or arc they reproduced? 



G 



