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BULLETIN OF THE BUKEAU OF FISHEEIES 
and 16), filling the waters of the bay and the eastern part of Vineyard Sound. The 
seasonal distribution of diatoms in Long Island Sound in 1922-23, during the 
winter months, was found to be very similar to that of Woods Hole except that the 
swarms appeared slightly later. 
Aotlnoptychas undulatus 
Aaterlonella japonica 
BacteriastrtDn delioatulum 
BiddulpMa alterans 
Biddulphia favus 
Biddulphla granulata 
Biddulphia blddulphlana 
BlddulpMa vesloTjlosa 
Corethron valdiviae 
Dltyllum tolghtwelll 
Kragllaria crotonensls 
Qcansiatophora marina 
(^asmatophora serpentina 
Colziardla flaoolda 
Hyalodlsctts stelllger 
loptooyllndrus danlous 
Uomophora flavsllata 
liomophora lyngbyel 
Ueloslra 'borrerl 
mtzsohla olosterlnm 
mtzsohla longlsslna 
Nltzsohla paradoza 
Bltzsehla serlata 
Paralla soloata 
BbaMonema adrlatlewn 
SkeletonoTTia oostattsn 
Strlatella xmlptmctata 
Syliedra galllonll 
Syaedxa tmdulata 
Thalasslosira deciplens 
Chalassloslra hyalina 
ThalasslOEira nordenskioldii 
Thalassiothris fratienf eldii 
Thalasslothris longissioa 
Thalasslothrlz nltzscMoides 
Dlstephams speonlum 
piotyoclia fllrala 
Cerataullna tergonll 
Cyolophora tennis 
Fig. 18.— Distribution of diatoms and Silicoflagellata in 1923 (excluding Chaetoceros and Rhizosolenia) 
The pelagic diatoms of the Woods Hole region may be grouped under three 
headings — tychopelagic, oceanic, and neritic. The tychopelagic group is made up 
of semi-bottom forms, which often occur in coastal waters in enormous numbers. 
They are carried about by the winds and tides, usually without relation to any 
