North American Centropagida. 23!) 



Limnocalanus macrurus, de Guerue et Richard, '89b. p. 77. PI. IV., 



Pig. 5, 11. 12. 

 Limnocalanus macrurus auctus, Forbes, '90, p. 6-18. 

 Limnocalanus macrurus, Marsh, *93. p. 201, PI. IV. Fig. 7. 

 Limnocalanus macrurus. Marsh, '95, p. 11, PI. IV., Fig. 1, 2; PI. V., 



Fig. 1-5. 

 Limnocalanus macrurus, Herrick and Turner, "95. p. 49, PI. I., Fig. 1-1. 

 Limnocalanus grimaldii, Sars, "97. p. 39, PI. IV., Fig. 1— IS. 



Body slender. Thorax rather more than one fourth as 

 broad as long, and composed of six well-defined segments, 

 of which the first (constricted at about the middle and armed 

 at the front with two hook-like processes pointing forward 

 and downward) is the longest — about equal to the three suc- 

 ceeding segments taken together; third and fourth segments 

 subequal, together slightly longer than the second, which is 

 armed on the dorsal and lateral surfaces, near the distal end, 

 with a row of rather stout spines; fifth segment somewhat 

 longer than the last, which is not produced laterally, hut 

 armed on each side with a very small spine. Abdomen of 

 Innale composed of four segments, the first about a third 

 longer than either of the two succeeding segments, which are 

 subequal. Furcal rami about a fifth longer than the first 

 segment, and slightly shorter than the second and third seg- 

 ments taken together; sparsely provided on the dorsal sur- 

 face with short sharp spines, and on the inner margin with 

 spines and hairs; one plumose seta on the outer margin at 

 the beginning of the distal fifth; and four plumose apical 

 setae and a delicate smooth seta on the dorsal surface near 

 the inner apical angle. In the male the first and fourth 

 abdominal segments are subequal, each about a fourth longer 

 than the fifth, which is the shortest ; second and third seg- 

 ments subequal, each about twice as long as the fifth ; second, 

 third, and fourth segments armed like the second abdominal 

 segment of the female. Furcal rami proportioned about as 

 in the female and similarly armed. 



Antenme 25-segmented ; right male antenna geniculate 

 between the lcSth and 19th segments. The armature of the 

 segments is as follows: 1 and 10 have a short seta and two 

 sense-hairs; 2, a short seta and three sense-hairs; 3, a short 



