Vou.2]  Hsterly—Copepoda of the San Diego Region. 135 
4. Eucalanus subtenuis Giesbrecht. 
Eucalanus subtenuis Giesbrecht, 1888, p. 3383; 1892, pp. 132, 150, 
pl. 11, figs. 4, 23, 42; pl. 35, figs. 9-11, 18, 29, 30; 1898, 
15 ale 
Fig. 9.—Eucalanus subtenuis. (a) Head of female, dorsal, X20. (b) 
Head of female, lateral, x 20. 
2 Genital segment somewhat longer than broad, between it 
and anal segment one free segment; forehead (fig. 9a) as in E. 
attenuatus, but less prolonged and not indented on sides. First 
joint of outer ramus of posterior antennae fused with second, 
first joint of inner ramus 3 times as long as broad, and as long 
as second joint; second basal of mandible with 2 bristles on inner 
border, first joint of inner ramus with 2 bristles, second with 4; 
second inner lobe of maxilla absent, third with 4 bristles, second 
basal with 4; same number on first joint of inner ramus of pos- 
terior maxilliped. 
4 Secondary sexual characters not pronounced; right fifth 
foot absent. 
Coloration: Transparent, without pigment. 
Length: Female, 2.7 mm. 
Occurrence: San Diego, June 16, 1904, one female. 
2. Genus Rhincalanus Dana. 
Calanus Dana, 1848, p. 11; 1849, p. 278. 
Rhincalanus Dana, 1852, p. 1082; 1855, pl. 76, figs. 2a-d. 
Rhincalanus Brady, 1883, p. 40. 
Rhincalanus Giesbrecht, 1888, p. 334; 1892, pp. 47, 152, 761; 
1898, p. 22. 
Rhincalanus Scott, T., 1893, p. 30. 
2 Five segments in cepalothorax (head and thorax fused), 
fourth and fifth thoracic segments distinct. Head similar to 
Eucalanus attenuatus, but produced into a snout-like process 
(fig. 10a). Abdominal and thoracic segments with spines; abdo- 
men with 3 segments, furca fused with last segment, and asym- 
