210 University of California Publications. | ZooLoGy 
2 Front blunt; furca as long as the anal segment, hardly 
twice as long as broad, outer marginal bristle about as long as 
the furea. Anterior antennae’ reach about to the posterior 
margin of the third thoracic segment. Second basal of mandible 
with one hooked bristle. Inner ramus of maxilla with four 
bristles. First, second and third (fig. 516), joints of outer ramus 
of first to third feet respectively, with one, one, three outer 
marginal bristles, of the fourth with one, one, two. 
& Division line between the first and second thoracic seg- 
ments with a sharp median projection; genital segment nar- 
rower than in O. plumifera. Proximal joint of the distal por- 
tion of the anterior antennae without the round process. Third 
joint of outer ramus of first to third feet with three outer mar- 
ginal bristles, of the fourth with two (fig. 51c). 
Coloration: Transparent, without pigment. 
Length: Female, 0.7-0.8 mm.; male, 0.5-0.6. 
Occurrence: Rather abundant in hauls taken from inside of 
the kelp beds at Point Loma. Both sexes found. The tow in 
which Oithona occurs most plentifully contains scarcely any 
other genera than Oncaea, Euterpe and Corycaeus. 
Fam. HARPACTICIDAE. 
1. Genus Microsetella Brady and Robertson. 
Microsetella Brady and Robertson, 1873, p. 130, pl. 9, figs. 11-16, 
Harpacticus Dana, 1847, p. 152. 
Canthocamptus Dana, 1852, p. 1187. 
Ectinosoma Brady, 1883, p. 99. 
Ectinosoma Mobius, 1887, p. 116. 
Microsetella Giesbrecht, 1892, pp. 78, 549, 750. 
2 Body eylindrical, smaller in front and behind, anterior 
portion with four segments, posterior with five; furca short, 
bristles very long. Anterior antennae 5-jointed, posterior 
3-jointed, outer ramus 3-jointed and slender. Rami of first to 
fourth feet 3-jointed, inner ramus longer than outer; fifth pair 
rudimentary and leaf-like (fig. 510). 
& Posterior portion of body with five segments, anterior 
antennae rather strong grasping organs; feet much smaller. 
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