Vou.2] Esterly—Copepoda of the San Diego Region. 139 
4 Characters as in the male of Calanus; the number of joints 
in the anterior antennae more reduced, the end-joint always 
shortened, and sometimes fused with the preceding one; fifth pair 
of feet weakly developed, the left 5-jointed, the right 4- or 2- 
jointed, or lacking. 
1. Genus Paracalanus Boeck. 
Calanus Claus, 1868, p. 172. 
Paracalanus Boeck, 1864, p. 8. 
Paracalanus Claus, 1881, p. 326. 
Paracalanus Bourne, 1889, p. 145. 
Paracalanus Giesbrecht, 1892, pp. 48, 164, 757; 1898, p. 23. 
Paracalanus Dahl, 1893, p. 21. 
Paracalanus Wheeler, 1899, p. 168. 
Second basal of first pair of feet with an inner marginal 
bristle; proximal division of outer border of third joint of outer 
ramus of fourth pair (fig. 12a) over twice as long as the distal; 
outer border of the second joint not dentate; proximal division 
of the outer border of third joint of outer ramus in the third and 
fourth feet dentate; sealpelliform terminal bristle of the outer 
ramus in the third pair longer than the end joint; second joint 
of inner ramus of first pair with 5, third of same in second pair 
with 7 bristles. The abdomen of the female (fig. 120) with 4 seg- 
ments; the last joint of anterior antennae less than 114 times as 
long as the next to the last. Fifth foot of female short, 2-jointed 
(fig. 12c) ; right foot of male with 2 joints, left with 5 (fig. 12c). 
2 Head fused with first thoracic segment, and fourth thoracic 
segment with fifth. Rostrum produced into two thin filaments. 
Genital segment and furea symmetrical, latter without bristle on 
outer margin. Anterior antennae with 25 joints. Outer ramus 
of posterior antennae shorter than inner; mandible with broad 
blade, the sack-like appendage on the first joimt of the inner 
ramus small. Maxilla with obscure segmentation of inner ramus, 
without bristle on the second lobe of outer border, and with but 
one on the first inner marginal lobe. Anterior maxilliped with 
outer marginal bristle. Inner ramus of the first swimming foot 
with 2 joints, of the second to fourth foot with 3 joints. 
4 Abdomen with 5 segments. Number of joints of anterior 
antennae reduced through fusion of joints 1 to 6 and 7 to 8, end 
joint shortened but free. Aesthetasks enlarged and numerous. 
