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Euterpe acutifrons Wolfenden, 1905 (a), p. 1034, pl. XCIX, figs. 18—2o0. 
Euterpe acutifrons Pearson, 1905, p. 7. 
Euterpe acutifrons Esterly, 1905, p. 212, fig. 53. 
Euterpina acutifrons Norman & T. Scott, 1906, p. 139. 
Euterpe acutifrons van Breemen, 1908, p. 176, fig. 191. 
Sixty specimens belonging to this species were obtained from the plankton collected at 
the following four stations in the area investigated by the ‘Siboga.’ 
Stat. 35. — Stat. 142. — Stat. 213. — Stat. 304. 
Euterpina acutifrons is readly recognised in preserved material by its arched body and 
very prominent rostrum, and by the moderately large foliaceous fifth pair of feet of the female. 
This Harpacticoid appears to be generally distributed in all the great oceans and appears 
to be subject to slight local variations. 
37. Family MACROSETELLIDAE nov. 
The body is very slender and cylindrical. The cephalic segment is large, and is fur- 
nished with a prominent beak-like rostrum. The abdomen is composed of four segments in the 
female. The furcal joints are rather long and slender. The antennules of the female are slender 
and nine-jointed. The last joint is moderately long and claw-like. The endopodite of the antennae 
is three-jointed. The exopodite is absent. The mandibles, maxillae and first pair of maxillipedes 
are rudimentary. The second pair of maxillipedes is prehensile and two-jointed. The second joint 
is furnished with an articulated claw. The exopodites of the first four pairs of feet are three- 
jointed. The endopodite of the first pair is two-jointed. The endopodites of the second, third 
and fourth pairs are three-jointed. The fifth pair of feet is two-jointed. The male is similar to 
the female except that the abdomen is five-jointed and the antennules are prehensile. The endo- 
podites of the first and second pairs of feet are two-jointed. The fifth pair is rather smaller. 
Genus Macrosetella nov. 
= Setella Dana, 1846, a name preoccupied by SCHRANK (Lefzdoptera), 1802. 
The only known member of this genus is easily identified by its slender body, by the 
long furcal joints and by the long antennules. 
The entire absence of the exopodite of the antennae, and the rudimentary condition of 
the mandibles, maxillae and first pair of maxillipedes indicate that the genus is worthy of more 
than generic rank. It is not related to MWzecrosetella or to any of the other members of the 
family Ectinosomidae. | 
The only representative of the genus appeared to be well distributed in the area investigated 
by the ‘Siboga’. 
1. Macrosetella gracilis (Dana). 
Setella gracilis Dana, 1852, p, 1198, pl. 84, fig. 3a—g. 
Setella messinensis Claus, 1863, p. 137, pl. XXI, figs. 15—16. 
230 
