1882. C'y 



1884. 



1887. 



1895. 



1895. 



1897. 



1909. 



Marsh — North American Species of Cyclops. 1071 



CYCLOPS ATER Herrick. 

 Plate, LXXII. figs. 1 to 6 and 9. 



lops ater Herrick, p. 228, pi. Ill, figs. 9-12. 

 p. 145, pi. Q, figs. 9-12. 

 p. 14. 

 " Herrick and Turner, p. 89, pi. VI, figs. 11-12. 

 •• Marsh, p. 13, pi. VI, figs. 1-4 and 6-12. 

 •• Forbes, p. 49, pi. XIV, pi. XV, figs 1-3. 

 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 equal, 

 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 

 cf 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 

 lias 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 ha9 

 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 



