Vou.2]  Hsterly— Copepoda of the San Diego Region. 128 
jointed inner and outer rami, and the number of outer marginal 
bristles on the outer ramus is the same in all the feet. The 
number of bristles on the inner ramus of the first pair is: one 
on the first joint, two on the second, six on the third (one on 
outer margin); on the terminal joint of the second and third 
pairs there are eight (two outer marginals). The fifth pair of 
feet in the male is always modified to form an accessory sexual 
organ: the right foot has a 2-jointed basal and is biramous, each 
ramus with three joints; the left foot has also a 2-jointed basal, 
and a 3-jointed outer ramus, while the inner ramus is reduced 
and may be entirely absent. 
1. Genus Calanus Leach. 
Monoculus Gunner, 1765. 
Calanus Leach, 1819, p. 539. 
Undina Dana, 1852, p. 1047. 
Cetochilus Claus, 1863, p. 169. 
Calanus Brady, 1883, p. 30. 
Calanoides Brady, 1883, p. 74. 
Undina Brady, 1883, p. 52. 
Calanus Giesbrecht, 1892, pp. 45, 88, 725. 
Calanus Dahl, 18946, p. 61. 
Calanus Dahl, 1898, p. 13. 
Calanus Wheeler, 1899, p. 164. 
2 Head free, or fused with thorax; fourth and fifth thoracic 
segments not fused. Abdomen with 4 segments, genital segment 
symmetrical, furea occasionally asymmetrical. Anterior antennae 
25-jointed, terminal joints with long, plumose bristles; the anten- 
nae vary in length, in some eases not reaching the posterior end 
of the body, in others extending beyond the furea (fig. 5a). 
Rami of posterior antennae of about equal lengths, outer ramus 
7-jointed. Inner ramus of maxilla 3-jointed. Anterior maxil- 
hped with long, curved bristles on inner border, outer border 
with a plumose bristle. Inner ramus of posterior maxilliped 
long, 5-jointed, bristles long and stiff, usually not plumose. 
Outer and inner rami of first to fourth pairs of feet 3-jointed, 
first, second and third joints of outer rami of all with 1, 1, 2 
marginal spines, respectively, terminal bristle sealpelliform, its 
margin smooth (fig. 1d). Inner ramus of first foot with 1, 2, 6 
bristles on the first, second and third joints in order; terminal 
