Vou.2] Ksterly—Copepoda of the San Diego Region. 127 
4, Anterior antennae bent into S-shape; joints 3, 4 and 5, and 
24 and 25 fused. Right fifth foot with 2 bristles on inner margin 
of third joint of outer ramus, terminal bristle short; terminal 
joint of left foot with three small bristles. 
Coloration: About as in C. finmarchicus. 
Leneth: Female, 1.8-2 mm.; male shghtly smaller. 
Occurrence: Not at all abundant, but coming in most catches 
with C. finmarchicus. 
38. Calanus tenuicornis Dana. 
Calanus tenuicornis Dana, 1849, p. 278; 1852, p. 1069; 1855, pl. 
73, figs. 10a, 10D. 
Calanus tenuicornis Giesbrecht, 1892, pp. 90, 129, pl. 6, figs. 12, 
HS plat, fes..0, LO 23s ple 8) esas s27 3 SO8tsn. 18: 
a 
b 
Fig. 8.—Calanus tenuicornis. (a) Male, lateral, X31. (b) Left fifth 
foot of male X83. 
? Head not fused with thorax; forehead and angles of last 
thoracic segment rounded; bristle of furca asymmetrical, outer 
marginal minute. Anterior antennae at least 114 times as long 
as the body. Proximal outer marginal spine of terminal joint 
of outer ramus in second to fourth feet, respectively, divides the 
margin into portions as 5:4, 10:7, 7:4. 
4 Anterior antennae as in Q, except for fusion of joints 1 
and 2, 3 to 5, 7 and 8, 9 and 10, 24 and 25. Mouth parts re- 
duced; no bristle on inner margin of outer ramus of either of 
the fifth feet; terminal bristle of right thorn-shaped, that of the 
left slender; inner rami of both feet similar. Basal portion and 
two proximal joints of outer ramus of right elongate, terminal 
joint shortened. 
Coloration: A variable amount of red or orange in antennae 
and mouth parts and oil drops of the same color in body. 
