North American Centropagidce. 245 



Limnocalanus sinensis Poppe. 



Limnocalanus sinensis, de Guerne et Richard, 89b, p. 79, PI. IV., 



Fig. 4, 15, 15a, 16. 

 Linmocalwius sinensis. Herriek and Turner, '95, p. JO. 



Body six- segmented, slender, more attenuate at the an- 

 terior than at the posterior part ; suture between' head and 

 thorax distinct. Second thoracic segment about as long as the 

 other five, which differ but little in length. Last two thoracic 

 segments distinct, the last segment somewhat produced pos- 

 teriorly and armed on each side with a short blunt spine. 

 First abdominal segment barely three times as long as the 

 second, which is but slightly longer than the fourth ; third 

 segment about one and three fourths times as long as the 

 second. Furcal rami more than twice as long as the third seg- 

 ment and barely four times as long as broad; somewhat 

 sparsely hairy within. All of the furcal seta? in both sexes dis- 

 tinctly plumose, the innermost seta much more slender than 

 the others and placed on the dorsal surface of the ramus, almost 

 directly opposite the base of the outer one. In the male the 

 first and fifth segments are subequal, each slightly longer 

 than the second and third, which are also about equal. 

 Fourth segment the shortest, about three fourths as long as 

 the second. Furcal rami fully three times as long as the 

 fourth segment, about four and a half times as long as 

 broad, and armed as in the female. 



Antenna; 25-segmented, hardly extending to the base of 

 the furca. Plight antenna of the male moderately swollen 

 from the 12th to the 18th segments inclusive. The armature 

 of the segments anterior to the 10th segment is as follows: 

 1 1 has a sense-club and a short seta ; 12, a sense-club, a short 

 seta, and a short curved spine; 13, a sense-hair and a sense- 

 club; 14, a sense-hair, a sense-club, and a long plumose 

 seta; 15, a sense-hair, a sense-club, and along spine; 1(5, a 

 sense-hair, a sense-club, and a long plumose seta; 17 a 

 broad knife-like process and a sense-club; 18, a short 

 stunted spine, another spine somewhat longer, and a hya- 

 line lamina armed with teeth about half as long as the lamina 

 is broad ; 19, 20, and 21 (completely ankylosed), a short 



