Marsh — North American Species of DiaptomiLS. 439 



The second segment is prolonged into the usual hook, which 

 is denticulate on the inner margin. The endopodite equals 

 the length of the first segment of the exopodite, and the tip is 

 armed with hairs and the two terminal spines. 



The fifth feet of the male are slender, and the left foot 

 reaches the distal end of the first segment of the right exopo- 

 dite. The first basal segments are armed with rather large 

 spines. The second basal segment of the right foot has the 

 lateral hair situated at about two-thirds of its length. The 

 length of this segment is about twice its width; it bears upon 

 the distal half of its inner margin a thin hyaline lamella, quad- 

 rangular in form. This projects rather from the posterior 

 surface than immediately from the inner margin. The second 

 segment of the exopodite is about twice the length of the first 

 segment. It bears a small spine on its inner margin at about 

 ona-third of its length. The lateral spins is small, curved, 

 and situated at about two-thirds of its length. The terminal 

 hook is falciform, symmetrically curved, and nearly equals in 

 length the rest of the foot. The right endopodite is small 

 and slender, and reaches about one-half the length of the first 

 segment of the exopodite. It is armed at the tip with minute 

 hairs. The lateral hair of the second basal segment of the 

 left foot is situated near the distal end of the segment. The two 

 segments of the exopodite are about equal in length and are 

 oval in form. The first segTuent is setose on its inner margin. 

 The second segment is swollen at the base on its inner margin 

 into a cushion which is setose. The tip is setose and armed 

 with two short finger-like processes. The endopodite is very 

 slender, reaches about one-half the length of the second segment 

 of the exopodite, and is hairy at the tip. 



The above description is like that of Lilljeborg with a few 

 corrections and additions. In his description he states that 

 there is a hyaline appendage of the first segment of the ex- 

 opodite of the male fifth foot that is "somewhat dilated." I:. 

 his figaire this appendage is made somewhat triangular in 

 form. In all the specimens I have seen, the appendage has 

 been distinctly quadrangular as I have figured it. I have not 



