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Euterpe acutifrons Wolfenden, 1905(0), p. 1034, pi. XCIX, figs. 18 — 20. 



Enter pc 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 Macrosetf.llidae 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 (Lepidoptera), 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 Microsetella 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, 1 198, pi. 84, fig. ^a — g. 

 Setella messinensis Claus, 1863, p. 137, pi. XXI, figs. 15 — 16. 



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