COPEPODS OF THE WOODS HOLE REGION 333 



of first three exopods with three outer spines, of fourth exopod with 

 only two spines ; inner margin of this segment in first legs with three, 

 in the following pairs with four, setae. Fifth legs 2-segmented, basal 

 segment more or less elongate, with one seta; distal segment short, 

 constricted at its base and 3-lobed at its tip, the middle lobe with a 

 slender seta, each outer lobe with a spine, the two unequal. 



KETT TO THE SPECIES 

 FEMALES 



1. Third and fourth segments of second antenna the same length, 



twice that of the second segment ; lamella on end segment of 



first antenna toothed fuscus (p. 333) 



Second and third segments of second antenna the same length, 

 fourth segment longer ; lamella on end segment of first antenna 

 smooth or lacking 2 



2. Lamella of end segment of first antenna well defined, smooth and 



forming a lappet at the tip of the segment albidus (p. 335) 



Lamella of end segment of first antenna entirely lacking, or if 

 present without a lappet at the tip of the segment bistriatus (p. 336) 



MACROCYLOPS FUSCUS (Jurine) 



FiGxmE 198 



Monociilus quadriconiis fuscus Jurine, Hist. Monocles, p. 47, pi. 2, fig. 2, 1820. 

 Cyolops signadus Koch, Deutschlands Crustaceen, Myriapoden und Arachniden, 



pt. 21, pi. 8, 1838. 

 Pachyctjclops signatns Sars, Crustacea of Norway, vol. 6, p. 65, pi. 40, 1914. 



Occurrence. — Both sexes found in a small pond near the outlet of 

 John Pond in Mashpee, in Jones Pond at Waquoit Village, and in 

 the pond on Rams Head Island in Hadley Harbor. 



Distribution. — Germany (Koch) ; Sweden (Lilljeborg) ; British 

 Isles (Brady) ; Poland (Lande) ; France (Richard) ; Norwegian 

 lakes and ponds, central Asia (Sars) ; Minnesota (Herrick) ; Wis- 

 consin, Michigan (Marsh) ; Illinois, Massachusetts (E. B. Forbes) ; 

 Nebraska (Pearse) ; Arkansas, Louisiana (Marsh). 



Color. — Body more or less transparent and of a dark greenish or 

 bluish color, variegated with brown; anterior antennae, legs, caudal 

 rami, and the last two abdominal segments bluish green; eggs dark 

 brown; eye reddish. 



Female. — Metasome ovate, twice as long as wide ; cephalic segment 

 considerably more than twice as long as the rest of the metasome; 

 fifth segment very small; urosome about one-third the length of 

 the metasome; genital segment as long as entire abdomen; caudal 

 rami a little longer than the anal segment, their inner margins finely 

 ciliated, the outer seta close to the tip. First antennae reaching the 

 end of the third segment; hyaline membrane on its end segment 

 coarsely dentate for the proximal half, finely denticulate or smooth 

 71937—32 23 



