284 WOLCOTT. [VOL. I. 



segments are nearly uniform in thickness from base to tip, 

 instead of tapering as do those of A. fossulatns, and the first pair 

 are hardly stouter than the others, while in A. fossulatns they 

 are considerably heavier. The claws are relatively longer and 

 slenderer, and all but those of the first pair seem to be simple 

 instead of bifid. The epimera are relatively shorter and broader, 

 and the acetabula are placed one behind the other in two 

 curved lines, as referred to above. 



This species has been taken at Grand Rapids, Mich., and 

 Milford and Lincoln, Neb., --176 specimens altogether, --and 

 the Nebraska specimens are peculiar in that the acetabula are 

 smaller and more closely crowded together, while the whole 

 sexual area is smaller than in the Michigan specimens. 



The writer has been uncertain whether this is a distinct 

 species or a variety of A. fossulatns, but for the present, at least, 

 has decided to consider it as separate, though closely allied. 



VI. A. arcuata n. sp. 



This species is equal in size to A. fossulatns ?cc\.&A.ypsilopJiorns, 

 between which it seems to be intermediate, and is of the same 

 elongated elliptical form. The palpi resemble very closely 

 those of A. ypsilopJwrns, as do also the epimera in size and 

 relationship to each other. The legs are very long, in the 

 male the fourth nearly half as long again as the body ; they 



are slender and the spines 

 are small and weak, while 

 they are characterized espe- 

 cially by the curved form of 

 the terminal segment, the 



FIG. 5. A. arcuata P anterior surface distal v i i 



segment, posterior pair of legs, x about I2S . curvature being only mocler- 



ate in the first pair, but in 



the fourth amounting to a deflection of 30. The distal 

 segment also tapers toward the tip, but just at the tip 

 is broadly expanded to receive the short, thick, bifid claw 

 (Fig. 5). The sexual area is toward the tip of the body and 

 resembles very closely in structure that of A. tinnidns ; the 

 general proportions are about those of A. ypsilopliorns, but 



