Marsh—North American Species of Cyclops. 
1071 
CYCLOPS ATER Herrick:. 
Plate, LXXII. figs. 1 to 6 and 9. 
1882. Cyclops ater Herrick, p. 228, pi. Ill, figs. 9-12. 
1884. “ “ 44 p. 145, pi. Q, figs. 9-12. 
1887. “ “ 44 p. 14. 
1895. “ 44 Herrick and Turner, p. 89, pi. VI, figs. 11-12. 
1895. 4 4 44 Marsh, p. 13, pi. VI, figs. 1-4 and 6-12. 
1897. 44 44 Forbes, p. 49, pi. XIV, pi. XV, figs 1-3. 
1909. 44 44 Byrnes, p. 5, pi. I, figs. 1 to 6. 
A large species, conspicuous both on account of its size and 
its brilliant colors. The cephalothorax is oval and very broad. 
The length and breadth of the first segment are about equals 
and this segment comprises more than two-thirds the entire 
length of the cephalothorax. The 'cephalothorax is nearly 
three times the length of the abdomen, exclusive of the furcal 
rami. 
The first abdominal segment is short and stout and very lit¬ 
tle enlarged at its anterior end. The succeeding segments are 
nearly equal in length, each being about one-third the length 
of the first segment. The posterior margin of the last seg¬ 
ment is armed with small spines. 
The furcal rami are about twice as long as wide. Herrick 
has a figure in which the furcal rami are ciliated on the inner 
margin. I do not find the cilia in my specimens, and Forbes 
(Forbes ’97) states that they are not ciliate. The lateral 
spine is situated near the end. Of the terminal setae, the 
outer is slightly shorter than the inner, the second is about 
twice as long as the outer, and the third about three times as 
long. 
The first antennae are 17-segmented and reach nearly 
the full length of the cephalothorax. The twelfth segment has 
a sensory club, and the sixteenth and seventeenth segments 
have a lateral hyaline lamella with an entire edge. This 
lamella, in the seventeenth segment projects as a blunt process 
beyond the end of the segment. 
The spinous armature on the terminal segments of the: 
