Bivalves 

Family Malletiidae, Yoldiidae,

& Glycymerididae





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Home > Northwest Shells & Marine Life > PNW Shells & Marine Life Photos > Bivalves >  Bivalves - Malletiidae, Yoldiidae,
                                                                                                                                                             & Glycymerididae







Malletiidae
Malletia pacifica
off coast of central Washington













Malletia pacifica Dall, 1897
Pacific Malletia
subtidal, 400-2900m          size to 35mm
south California to south Alaska
This is a very deep water species and has a very polished periostracum.  This specimen was found ex pisce.



















Yoldia seminuda
Victoria, BC
Yoldia seminuda Dall, 1871
Oblique-Lined Yoldia
subtidal, 15-375m        size to 40mm
southern California to Bering Sea; northern Japan to Sea of Okhotsk
It has an elongated, thin shell. The periostracum is adherent and shiny yellow to dark brown.
(synonyms - Nucula arctica,Yoldia scissurata)
Yoldia myalis
San Juan Islands, WA
Yoldia myalis (Couthouy, 1838)
Oval Yoldia
subtidal, 20-165m          size to 30mm
northern Washington to Bering Sea; Maine to
Hudson Bay and also Sea of Okhotsk
The posterior end is broadly rounded.  The dark
 brown periostracum may be dull or silky.
(synonyms - Nucula myalis, Yoldia vancouvernesis)
Megayoldia thraciaeformis
San Juan Islands, WA
Megayoldia thraciaeformis
(Storer, 1838)
Broad Yoldia
subtidal, 25-760m          size to 65mm
central California to Bering Sea; Japan 
It is distinguished by a quadrate shape
and broadly truncated posterior end.
(synonyms - Nucula thraceaeformis,
Yoldia secunda)
















































This page last revised: 5-25-2019
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Glycymerididae
Glycymeris septentrionalis Glycymeris septentrionalis
                                                       Barkley Sound, BC                                                                   off Whidbey Island, WA, from subtidal
Glycymeris septentrionalis (Middendorff, 1849)
Western Bittersweet
intertidal to 400m          northern Mexico to southern Alaska          size to 45mm
It can be found intertidally at good low tides.  It has a chalky white shell with brown flecks and maculations.  There are numerous teeth on the
shell margin and on either side of the hinge.  The hinge size and shell sculpture can vary widely.  The interior is often yellow with brown stains.
(synonyms - Pectunculus septentrionalis, Glycymeris subobsoleta, Glycymeris profunda)
Yoldiidae
Megayoldia martyria
Sidney Channel, BC
Megayoldia martyria (Dall, 1897)
Witness Yoldia
subtidal, 100-330m          north Mexico to south BC          size to 30mm
The shell is smooth with a shiny periostracum.
         (previous name - Yoldia martyria)
Click on photo to enlarge.  Scale line in photo equals 1cm unless otherwise specified.
 * Species which are commonly encountered on the beach.