ANNELIDES. 
281 
in quoque segmento, cirris postoccipitalibus longitudinem capitis asquan- 
tibiis, pinnis (ramis) in segmentis duobus primis exceptis, brevissimis, 
branchiis bipartitis basi pinnarum affixis. 
Of Nereides nineteen species are enuinerrated. Oersted divides the 
genus Nereis into the sub-genera, Nereis, L,, Lycoris, Sav., and Hetero- 
nereis, Oerst. ; the latter principally characterized by its anteriorly 
twisted round, and posteriorly flattened body. To Nereis pelagica, 
and diversicolor ; Phyllodoce maculata, Syllis armillaris, Eulalia 
viridis ; Eteone Jlava and longa, and Nephtys cceca, all of which 
Fabricius has mentioned. Oersted adds the following; — Heteronereis 
paradoxa, Oerst. {Nereis longissima, Johnston ?) ; Heteronereis assimi- 
lis, Oerst. {Nereis renalis, Johnst. ?) ; and Heteronereis arctica, Oerst., 
eapite elongate conico 4-5 segmenta sequentia longitudine sequante, 
maxillis parum tortis crenulatis, parte antica corporis ex 20 segmentis 
constante lobis pinnarum partis anticac omnibus abbreviatis rotundatis, 
cirro superiore quater vel quinquies longiore quam lobo prime ; in parte 
postica lobo prime subacuminato, ceteris abbreviatis rotundatis, cirro 
superiore prominentiis 9-10 distinctis praedito. 
PoLYBosTRicHus is characterized as a new genus, with the following 
diagnosis : — Corpus lineare depressum ex duabus partibus, anteriore et 
posteriore forma inter se discrepantibus, constans. Caput appendicibus 
tentacularibus 11 instructum, palpi duo minuti, 4 tentacula, cirri tenta- 
culares quinque. Os inferum absque maxillis. Oculi duo. In antica cor- 
poris parte pinnas connatas setis falcatis prasditae, in postica pinnae 
discretae, in superiore setae composite falcatae. Cirrus superior diversae 
formae in antica et postica corporis parte, cirrus inferior nullus. This 
genus is represented by P. longisetosa, Oerst. {Nereis corniculata, 
Miill. ?) 
Phyllodoce groenlandicct is new ; corpore viridi depresso, eapite cor- 
date paulo latiore quam longiore antice truncate, cirris tentacularibus in 
segmentis duobus anterioribus affixis, segmentis brevissimis, branchia 
superiore subrectangulari verticali, branchia inferiore subelliptica in 
mediis segmentis apice sursum versa, setis capillaribus 30-40. Another 
new species, Phyllodoce incisa, Oerst., may perhaps serve for founding 
a separate genus ; corpore virescenti teretiusculo, eapite conico duplo 
longiore quam latiore, cirris tentacularibus in segmentis duobus anteri- 
oribus affixis, segmentis mediis longitudine latitudinem corporis aequan- 
tibus subhexagonis, ceteris utramque extremitatem versus regulariter 
decrescentibus, branchia superiore subpentagona subhorizontali. 
Eteone cylindrica is mentioned as new by Oersted, with the follow- 
ing diagnosis : — Corpore tereti, eapite abbreviate conico, branchia 
superiore compressa subovali a pinna valde remota. 
Nephtys longisetosa. Oersted, is also new ; lamella superiore trian- 
gulari acque longa ac pinna, cirro superiore nullo, spatio inter pinnas 
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