Abietinaria abietina (Linnaeus, 1758) (additional source)
Abietinaria filicula (Ellis & Solander, 1786) (additional source)
Acanthodoris pilosa (Abildgaard, 1789) (additional source)
Acanthonotozoma serratum (O. Fabricius, 1780) (additional source)
Acaulis primarius Stimpson, 1853 (additional source)
Achelia spinosa (Stimpson, 1853) (additional source)
Aclis striata A. E. Verrill, 1880 accepted as Odostomia striata (A. E. Verrill, 1880) (basis of record)
Acmira catherinae (Laubier, 1967) represented as Aricidea (Acmira) catherinae Laubier, 1967 (additional source)
Acrocirrus leidyi Verrill, 1882 accepted as Macrochaeta leidyi (Verrill, 1882) (basis of record)
Adalaria proxima (Alder & Hancock, 1854) (additional source)
Aeginina longicornis (Krøyer, 1843) (additional source)
Aequorea albida A. Agassiz, 1862 (additional source)
Aeverrillia setigera (Hincks, 1887) (basis of record)
Agalma elegans (M. Sars, 1846) (additional source)
Aglantha digitalis (O.F. Mueller, 1776) accepted as Aglantha digitale (O. F. Müller, 1776) (additional source)
Alvania pseudoareolata Warén, 1974 (additional source)
Amblyosyllis cincinnata (Verrill, 1874) accepted as Amblyosyllis finmarchica (Malmgren, 1867) (basis of record)
Amblyosyllis finmarchica (Malmgren, 1867) (additional source)
Ampelisca macrocephala Liljeborg, 1853 (additional source)
Ampelisca vadorum Mills, 1963 (additional source)
Ampharete acutifrons (Grube, 1860) (additional source)
Ampharete cirrata Webster & Benedict, 1887 (additional source)
Ampharete trilobata Webster & Benedict, 1887 (basis of record)
Amphipholis squamata (Delle Chiaje, 1828) (additional source)
Amphiporeia lawrenciana Shoemaker, 1929 (additional source)
Amphiporus angulatus (Müller, 1774) (additional source)
Amphiporus bioculatus sensu Verrill, 1892 (additional source)
Amphiporus caecus Verrill, 1892 (additional source)
Amphiporus frontalis Verrill, 1892 (additional source)
Amphiporus groenlandicus Ørsted, 1843 (additional source)
Amphiporus heterosorus Verrill, 1892 (additional source)
Amphiporus lactifloreus (Johnston, 1828) (additional source)
Amphitrite brunnea (Stimpson, 1853) (basis of record)
Amphitrite cirrata Müller, 1776 (additional source)
Amphitrite johnstoni Malmgren, 1866 accepted as Neoamphitrite figulus (Dalyell, 1853) (additional source)
Amphitrite ornata (Leidy, 1855) (additional source)
Ampithoe rubicata (Montagu, 1808) accepted as Ampithoe rubricata (Montagu, 1808) (additional source)
Anaitides groenlandica (Örsted, 1842) accepted as Phyllodoce groenlandica Örsted, 1842 (additional source)
Anaitides maculata (Linnaeus, 1767) accepted as Phyllodoce maculata (Linnaeus, 1767) (additional source)
Anaitides mucosa (Örsted, 1843) accepted as Phyllodoce mucosa Örsted, 1843 (additional source)
Anaperus gardineri (Graff, 1911) accepted as Thalassoanaperus gardineri (Graff, 1911) (basis of record)
Anomia simplex A. d'Orbigny, 1853 (additional source)
Anomia squamula Linnaeus, 1758 accepted as Heteranomia squamula (Linnaeus, 1758) (additional source)
Anonyx lilljeborgi Boeck, 1871 (additional source)
Anonyx sarsi Steele & Brunel, 1968 (additional source)
Anoplodactylus lentus Wilson, 1878 (additional source)
Antalis entale stimpsoni (J. B. Henderson, 1920) accepted as Antalis entale (Linnaeus, 1758) accepted as Antalis entalis (Linnaeus, 1758) (additional source)
Aphanostoma sanguineum Beklemischev, 1915 accepted as Pseudactinoposthia sanguineum (Beklemischev, 1915) (basis of record)
Apistobranchus tullbergi (Théel, 1879) (additional source)
Aplidium glabrum (Verrill, 1871) (additional source)
Aplidium pallidum (Verrill, 1871) (additional source)
Aporrhais occidentalis (H. Beck, 1836) accepted as Arrhoges occidentalis (H. Beck, 1836) (additional source)
Arabella iricolor (Montagu, 1804) (additional source)
Arenicola marina (Linnaeus, 1758) (additional source)
Aricidea nolani Webster & Benedict, 1887 (basis of record)
Aricidea quadrilobata Webster & Benedict, 1887 represented as Aricidea (Strelzovia) quadrilobata Webster & Benedict, 1887 (additional source)
Artacama proboscidea Malmgren, 1866 (additional source)
Ascidia callosa Stimpson, 1852 (additional source)
Ascidia prunum Müller, 1776 (additional source)
Astarte borealis (Schumacher, 1817) accepted as Tridonta borealis Schumacher, 1817 (additional source)
Astarte castanea (Say, 1822) accepted as Isocrassina castanea (Say, 1822) (additional source)
Astarte elliptica (T. Brown, 1827) accepted as Tridonta elliptica (T. Brown, 1827) (additional source)
Astarte undata A. Gould, 1841 (additional source)
Asterias forbesi (Desor, 1848) (additional source)
Asterias rubens Linnaeus, 1758 (additional source)
Astrotorhynchus bifidus (McIntosh, 1874) Graff, 1905 (additional source)
Astyris lunata (Say, 1826) (additional source)
Astyris rosacea (A. Gould, 1840) (additional source)
Aulactinia stella (Verrill, 1864) (additional source)
Aurelia aurita (Linnaeus, 1758) (additional source)
Autolytus cornutus Agassiz, 1862 accepted as Proceraea cornuta (Agassiz, 1862) (additional source)
Autolytus prolifera (O.F. Müller, 1788) accepted as Myrianida prolifera (O.F. Müller, 1788) (additional source)
Autolytus varians Verrill, 1881 (basis of record)
Autolytus verrilli Marenzeller, 1892 accepted as Epigamia alexandri (Malmgren, 1867) (additional source)
Balanus balanus (Linnaeus, 1758) (additional source)
Balanus crenatus Bruguière, 1789 (additional source)
Bolinopsis infundibulum (O.F. Müller, 1776) (additional source)
Boltenia echinata (Linnaeus, 1767) (additional source)
Boltenia ovifera (Linnaeus, 1767) (additional source)
Bopyroides hippolytes (Kröyer, 1838) (additional source)
Boreotrophon clathratus (Linnaeus, 1767) (additional source)
Boreotrophon truncatus (Strøm, 1768) (additional source)
Bostrichobranchus pilularis (Verrill, 1871) (additional source)
Botrylloides diegense Ritter & Forsyth, 1917 accepted as Botrylloides diegensis Ritter & Forsyth, 1917 (additional source)
Botryllus schlosseri (Pallas, 1766) (additional source)
Bougainvillia superciliaris (L. Agassiz, 1849) (additional source)
Bowerbankia gracilis Leidy, 1855 accepted as Amathia gracilis (Leidy, 1855) (additional source)
Brada granosa Stimpson, 1853 (additional source)
Brada setosa Verrill, 1873 accepted as Bradabyssa setosa (Verrill, 1873) (basis of record)
Brada sublaevis Stimpson, 1853 (basis of record)
Brada villosa (Rathke, 1843) accepted as Bradabyssa villosa (Rathke, 1843) (additional source)
Buccinum ciliatum (O. Fabricius, 1780) (additional source)
Buccinum polaris Gray, 1839 accepted as Buccinum polare Gray, 1839 (additional source)
Bugula fulva Ryland, 1960 accepted as Bugulina fulva (Ryland, 1960) (additional source)
Bugula simplex Hincks, 1886 accepted as Bugulina simplex (Hincks, 1886) (additional source)
Bugula turrita (Desor, 1848) accepted as Crisularia turrita (Desor, 1848) (additional source)
Byblis gaimardi (Krøyer, 1846) accepted as Byblis gaimardii (Krøyer, 1846) (additional source)
Byblis serrata S.I. Smith, 1873 (additional source)
Caberea ellisii (Fleming, 1814) (additional source)
Caecognathia elongata (Krøyer, 1847) (additional source)

Cobscook Bay for Abietinaria abietina (Linnaeus, 1758) 
Cobscook Bay for Abietinaria filicula (Ellis & Solander, 1786) 
Cobscook Bay for Acanthodoris pilosa (Abildgaard, 1789) 
Cobscook Bay for Acanthonotozoma serratum (O. Fabricius, 1780) 
Cobscook Bay for Acaulis primarius Stimpson, 1853 
Cobscook Bay for Achelia spinosa (Stimpson, 1853) 
Cobscook Bay for Acirsa borealis (Lyell, 1841) 
Cobscook Bay for Aclis striata A. E. Verrill, 1880 
Cobscook Bay for Acmira catherinae (Laubier, 1967) 
Cobscook Bay for Acrocirrus leidyi Verrill, 1882 
Cobscook Bay for Adalaria proxima (Alder & Hancock, 1854) 
Cobscook Bay for Admete viridula (O. Fabricius, 1780) 
Cobscook Bay for Aeginina longicornis (Krøyer, 1843) 
Cobscook Bay for Aeolidia papillosa (Linnaeus, 1761) 
Cobscook Bay for Aequorea albida A. Agassiz, 1862 
Cobscook Bay for Aeverrillia setigera (Hincks, 1887) 
Cobscook Bay for Agalma elegans (M. Sars, 1846) 
Cobscook Bay for Aglantha digitalis (O.F. Mueller, 1776) 
Cobscook Bay for Alaurina composita Metschnikoff, 1861 
Cobscook Bay for Alvania pseudoareolata Warén, 1974 
Cobscook Bay for Amblyosyllis cincinnata (Verrill, 1874) 
Cobscook Bay for Amblyosyllis finmarchica (Malmgren, 1867) 
Cobscook Bay for Ampelisca macrocephala Liljeborg, 1853 
Cobscook Bay for Ampelisca vadorum Mills, 1963 
Cobscook Bay for Ampharete acutifrons (Grube, 1860) 
Cobscook Bay for Ampharete cirrata Webster & Benedict, 1887 
Cobscook Bay for Ampharete trilobata Webster & Benedict, 1887 
Cobscook Bay for Amphipholis squamata (Delle Chiaje, 1828) 
Cobscook Bay for Amphiporeia lawrenciana Shoemaker, 1929 
Cobscook Bay for Amphiporus angulatus (Müller, 1774) 
Cobscook Bay for Amphiporus bioculatus sensu Verrill, 1892 
Cobscook Bay for Amphiporus caecus Verrill, 1892 
Cobscook Bay for Amphiporus frontalis Verrill, 1892 
Cobscook Bay for Amphiporus groenlandicus Ørsted, 1843 
Cobscook Bay for Amphiporus heterosorus Verrill, 1892 
Cobscook Bay for Amphiporus lactifloreus (Johnston, 1828) 
Cobscook Bay for Amphitrite brunnea (Stimpson, 1853) 
Cobscook Bay for Amphitrite cirrata Müller, 1776 
Cobscook Bay for Amphitrite johnstoni Malmgren, 1866 
Cobscook Bay for Amphitrite ornata (Leidy, 1855) 
Cobscook Bay for Ampithoe rubicata (Montagu, 1808) 
Cobscook Bay for Anaitides groenlandica (Örsted, 1842) 
Cobscook Bay for Anaitides maculata (Linnaeus, 1767) 
Cobscook Bay for Anaitides mucosa (Örsted, 1843) 
Cobscook Bay for Anaperus gardineri (Graff, 1911) 
Cobscook Bay for Ancula gibbosa (Risso, 1818) 
Cobscook Bay for Anisakis simplex (Rudolphi, 1809) Dujardin, 1845 
Cobscook Bay for Anomia simplex A. d'Orbigny, 1853 
Cobscook Bay for Anomia squamula Linnaeus, 1758 
Cobscook Bay for Anonyx lilljeborgi Boeck, 1871 
Cobscook Bay for Anonyx nugax (Phipps, 1774) 
Cobscook Bay for Anonyx sarsi Steele & Brunel, 1968 
Cobscook Bay for Anoplodactylus lentus Wilson, 1878 
Cobscook Bay for Antalis entale stimpsoni (J. B. Henderson, 1920) 
Cobscook Bay for Antalis entalis (Linnaeus, 1758) 
Cobscook Bay for Aphanostoma sanguineum Beklemischev, 1915 
Cobscook Bay for Aphrodita aculeata Linnaeus, 1758  (doubtful)
Cobscook Bay for Aphrodita hastata Moore, 1905 
Cobscook Bay for Apistobranchus tullbergi (Théel, 1879) 
Cobscook Bay for Aplidium glabrum (Verrill, 1871) 
Cobscook Bay for Aplidium pallidum (Verrill, 1871) 
Cobscook Bay for Aporrhais occidentalis (H. Beck, 1836) 
Cobscook Bay for Arabella iricolor (Montagu, 1804) 
Cobscook Bay for Arctica islandica (Linnaeus, 1767) 
Cobscook Bay for Arenicola marina (Linnaeus, 1758) 
Cobscook Bay for Aricidea nolani Webster & Benedict, 1887 
Cobscook Bay for Aricidea quadrilobata Webster & Benedict, 1887 
Cobscook Bay for Artacama proboscidea Malmgren, 1866 
Cobscook Bay for Ascidia callosa Stimpson, 1852 
Cobscook Bay for Ascidia prunum Müller, 1776 
Cobscook Bay for Astarte borealis (Schumacher, 1817) 
Cobscook Bay for Astarte castanea (Say, 1822) 
Cobscook Bay for Astarte crenata (J. E. Gray, 1824) 
Cobscook Bay for Astarte elliptica (T. Brown, 1827) 
Cobscook Bay for Astarte subaequilatera G. B. Sowerby II, 1854 
Cobscook Bay for Astarte undata A. Gould, 1841 
Cobscook Bay for Asterias forbesi (Desor, 1848) 
Cobscook Bay for Astrotorhynchus bifidus (McIntosh, 1874) Graff, 1905 
Cobscook Bay for Astyris lunata (Say, 1826) 
Cobscook Bay for Astyris rosacea (A. Gould, 1840) 
Cobscook Bay for Autolytus cornutus Agassiz, 1862 
Cobscook Bay for Autolytus prolifera (O.F. Müller, 1788) 
Cobscook Bay for Autolytus varians Verrill, 1881 
Cobscook Bay for Autolytus verrilli Marenzeller, 1892 
Cobscook Bay for Balanus balanus (Linnaeus, 1758) 
Cobscook Bay for Balanus crenatus Bruguière, 1789 
Cobscook Bay for Bathypolypus bairdii (A. E. Verrill, 1873) 
Cobscook Bay for Bolinopsis infundibulum (O.F. Müller, 1776) 
Cobscook Bay for Boltenia echinata (Linnaeus, 1767) 
Cobscook Bay for Boltenia ovifera (Linnaeus, 1767) 
Cobscook Bay for Bopyroides hippolytes (Kröyer, 1838) 
Cobscook Bay for Boreotrophon clathratus (Linnaeus, 1767) 
Cobscook Bay for Boreotrophon truncatus (Strøm, 1768) 
Cobscook Bay for Bostrichobranchus pilularis (Verrill, 1871) 
Cobscook Bay for Botrylloides diegense Ritter & Forsyth, 1917 
Cobscook Bay for Botryllus schlosseri (Pallas, 1766) 
Cobscook Bay for Bougainvillia superciliaris (L. Agassiz, 1849) 
Cobscook Bay for Bowerbankia gracilis Leidy, 1855 
Cobscook Bay for Brada granosa Stimpson, 1853 
Cobscook Bay for Brada setosa Verrill, 1873