246 



THE AMERICAN NATURALIST [Vol. XL 



have been examined from Arlington, Brighton, Cambridge, and 

 Wood's Hole, which were taken in June, July, and August. It 

 therefore seems probable that this species is common in eastern 

 Massachusetts during the summer months. 



Figs. 6-9 



Description. — Cephalothorax robust and 

 six-segmented. The first segment is three 

 fourths the length of the cephalothorax, shows 

 a dorsal transverse groove at about its middle. 

 Last two segments indistinct on the dorsal 

 surface. Last segment produced posteriorly 

 and armed with two sharp spines on each side 

 (Fig. 7) . Abdomen stout, first segment long- 

 er than the remainder of the abdomen; sec- 

 ond segment one sixth as long as first and one 

 half as long as third. Furcal rami one fourth 

 longer than wide ; hairy on inner margin. 



Antennae twenty-five-segmented; those of 

 the female extending to the tips of the furca. 



Right antenna of male (Fig. 6) geniculate; 

 swollen from the eleventh segment to the 

 geniculate joint; twelfth 



segment arn 

 strong poini 



ed with a 



ed process 



trie segment is wide; 

 ninth and tenth segments 

 armed with shorter proc- 

 esses; antepenultimate 

 segment armed with a 



little 



light antenna, r 



as long as the penulti- 

 mate segment. 



Fifthfeetof male (Fig. 

 i) characteristic. First basal segment of left foot ^'^patJio^cnai 

 •eaching almost to end of first segment of outer sideoffemal 

 •am us of right fifth foot; as wide as long; armed end of cephj 

 m the posterior surface with a long slender spine ^ ^3®- 

 it the outer distal angle. Second basal segment two thirds 



