178 



BULLETIN 46, UNITED STATES NATIONAL MUSEUM. 



.Etymology. — Sew, six; spinosus, spiny. 



Comparisons of northern and southern specimens show, as we pro- 

 ceed southwards, the following' differences : 



(1). An increase in size, especially in the anal legs, which are more 

 slender. 



(2). An increase in size in the femoral spines of anal legs. 



(3) A tendency among some of the more southern specimens for the 

 coxse of the prehensorial legs to become dentate. 



(4) A tendency for the lateral margins of anal segment to become 

 more callous and slightly serrulate. 



(5) An increase in the density of the general coloration and an in- 

 crease in the paleness of the anal legs beneath. 



The following table shows the increase in size of the anal pair of legs : 



Habitat. 



Total length. 



Length of 

 anal. 





mm. 

 45 

 37 

 50 

 32 

 48 

 55 

 42 

 58 

 65 

 35 

 35 



mm. 

 7.8 

 8.4 

 9.4 

 7.7 



11.5 



17. 



10.7 



14.6 



18. 

 7.7 



10. 



Chicago, 111 







Chapel Hill, N. C 



Mossv Creek, Tenn 



Eaglet on, Indian Ter 



Indian Springs, Ga 



Do 





The increase in length of legs is more noticeable in specimens from 

 the southeast portion of the United States, while toward the southwest 

 they tend to be more like the northern. 



As all my specimens from Pensacola are small I have compared them 

 with one of the same size from Georgia. 



Some specimens from Winona and Chicago have the interior spine 

 of anal legs absent. 



The specimen from Baltimore has the tibia and tarsi of anal legs 

 pilose, the hairs being much longer than those of other specimens; the 

 other legs are rather sparsely pilose. 



Those from Indian Springs seem to represent Scolop. georgicus of 

 Meinert; although the anal legs are longer, the first 4 dorsal plates im- 

 marginate, and the prosternum slightly dentate, I believe it should not 

 be considered as a good species. 



14/). Scolopocryptops sexspinosus spinicaudus. 



1862 — Scolopocryptops sphiicaucla Wood. Jouni. Acad. Nat. Sci. Phila., 39(Shoal Water 

 Bay, W. T.; Oregon); Wood, Trans. Amer. Phil. Soc, 174, 1865; Wood, Proc. 

 Acad. Nat. Sci. Phila., 128, 1867 (San Jose, Cat.). 



Habitat. — Shoal Water Bay and Chehalis, W. T.; Oregon; San Jose 

 and San Mateo, California. 

 Etymology. — Latin, spina, spine; cauda, tail. 



