174 University of California Publications. | ZOOLOGY 
like those of the Calanidae. The first four pairs of feet usually 
with 3-jointed rami, in which, however, the two proximal Joints 
may be fused; inner ramus absent in fifth pair, or small and 
1-jointed ; the outer ramus is 1- to 3-jointed. 
4 Grasping antenna usually the right; distally from the 
geniculation, the nineteenth and twenty-first and twenty-second 
and twenty-third joints are fused; sexual peculiarities often in 
the swimming feet as well as in the form of the body, anterior 
antennae and fifth pair of feet. 
1. Genus Pleuromamma Giesbrecht. 
Diaptomus Lubbock, 1856, p. 27. 
Pleuromma Claus, 1863, p. 195. 
Pleuromma Brady, 1883, p. 45. 
Pleuromma Giesbrecht, 1892, pp. 61, 347, 757. 
Pleuromma Dahl, 1893, p. 105. 
Pleuromma Wheeler, 1899, p. 176. 
Pleuromamma Giesbrecht, 1898, p. 108. 
Easily recognizable by a dark-pigmented knob on the right 
or left side of the first thoracic segment (figs. 33a, 34a). Furea 
at most twice as long as broad. Rami of the first to fourth pairs 
of feet 3-jointed, first joint of outer ramus of third pair with a 
deep notch in the outer border; terminal bristle of outer ramus 
of third pair short and bent outward; first joint of inner ramus 
of second pair with hooks on inner border, on right and left foot 
in the female, usually on one side in male. Fifth pair in female 
rudimentary, 2- to 4-jointed, in male 5-jointed on each side, 
without forceps. Grasping antenna of male on right or left 
side. Abdomen of female with three segments; of male with 
five, sometimes asymmetrical. 
1. Pleuromamma abdominalis Lubbock. 
Diaptomus abdominale Lubbock, 1856, p. 28, pl. 10, figs. 1-8. 
Pleuromma abdominale Claus, 1863, p. 197, pl. 5, figs. 1-6, 13, 
14; pl. 6, fig. 1-10. 
Pleuromma abdominale Brady, 1883, p. 46, pl. 11, figs. 1-13. 
Pleuromma abdominale Giesbrecht, 1892, pp. 347, 357, pl. 5, fig. 
8; pl. 32, figs. 3, 5, 13, 22, 25-30; pl. 33, figs. 43, 44, 48, 
49, 52. 
Pleuromamma abdominalis Giesbrecht, 1898, p. 109. 
