PLANKTON OF THE OFFSHORE WATERS OF THE GULF OF MAINE 
ae* 
By HENRY B. BIGELOW 
Museum of Comparative Zoology, Harvard University 
With tables of copepods by C. B. Wilson, and tables of diatoms by Albert Mann 
CONTENTS 
Page 
Introduction 5 
The plankton 15 
Section 1. — General survey of the animal 
plankton (zooplankton) 16 
Vertical distribution 24 
Neritic and oceanic plankton 31 
Seasonal fluctuations in the planktonic 
communities 37 
Immigrant planktonic communities 51 
Tropical visitors 53 
Arctic visitors 59 
Other immigrants 62 
Migrations of pelagic fish eggs and 
larvae 69 
Quantitative distribution 78 
Density of association 90 
Annual variations in abundance 96 
Plankton as food for whales and fishes. 97 
Food of the plankton 106 
The more important groups of plank- 
tonic animals 112 
Mollusks 112 
Cephalopods . 112 
Pteropods 116 
Limacina retro versa 116 
Limacina helicina 125 
Clione limacina 125 
Other pelagic mollusks 129 
Crustaceans 130 
Adult decapods 130 
Pasiphaea 131 
Euphausiids 133 
Thysanoessa inermis 135 
Thysanoessa longicaudata 139 
Thysanoessa gregaria 142 
Thysanoessa raschii 143 
Nematoscelis megalops 146 
Page 
Section 1 . — General survey of the animal 
plankton (zooplankton) — Continued. 
The more important groups of plank- 
tonic animals — Continued. 
Crustaceans — Continued. 
Euphausiids — Continued. 
Euphausia krohnii 146 
Meganyctiphanes norvegica 147 
Thysanopoda acutifrons 155 
Other euphausiids 155 
Hyperiid amphipods 156 
Euthemisto 156 
Other hyperiids-: : 165 
Hyperia 165 
Hyperoche 165 
Parathemisto oblivia 166 
Oceanic hyperiids 166 
Copepods 167 
Acartia clausi.. 171 
Aeartia longiremis 177 
Acartia tonsa 181 
ADtidius armatus 182 
Anomalocera pattersoni 182 
Asterocheres bcecki 187 
Calanus finmarchicus 188 
Calanus gracilis 211 
Calanus hyperboreus 212 
Candacia armata 218 
Centropages bradyi 219 
Centropages hamatus 220 
Centropages typicus 221 
Dactylopusia thisboides 226 
Dwightia gracilis 226 
Ectinosoma neglectum 227 
Eucalanus attenuatus 228 
Eucalanus elongatus 228 
Euchseta media 230 
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