. Bulletin of the Natural History Museum Zoology. DEEP-SEA PROTOBRANCHIA (BIVALVIA) Material: Cruise Sta Depth No (m) Lat Long Date Gear ANGOLA BASIN Atlantis II 203 42 527- 31 542 08''S 12° ES Distribution. Restricted to the Angola Basin at upper slope depths, 527-542 metres. Shell description () Elongate, fragile, transluscent shell, moderately slender, two cari- nate ribs from umbo to posterior margin, widely spaced prominant, relatively broad, concentric ribs with overhanging ventral margin, 2-A fine concentric lines between ribs, between carinae vertical ribs and
. Bulletin of the Natural History Museum Zoology. DEEP-SEA PROTOBRANCHIA (BIVALVIA) Material: Cruise Sta Depth No (m) Lat Long Date Gear ANGOLA BASIN Atlantis II 203 42 527- 31 542 08''S 12° ES Distribution. Restricted to the Angola Basin at upper slope depths, 527-542 metres. Shell description () Elongate, fragile, transluscent shell, moderately slender, two cari- nate ribs from umbo to posterior margin, widely spaced prominant, relatively broad, concentric ribs with overhanging ventral margin, 2-A fine concentric lines between ribs, between carinae vertical ribs and lines equally prominant; umbo moderately raised, far anterior in largest specimens (post-umbonal length 79% of total length) but less so in smaller specimens, beaks inwardly facing; antero-dorsal mar- gin sloping, proximally convex but almost straight in small specimens, joins with anterior and antero-ventral margins in smooth curve; postero-ventral margin very slightly sinuous, posterior margin usu- ally damaged in large specimens, intact margin angled and sinuate, forming a hook dorsally where postero-dorsal margin and dorsal carina meet, postero-dorsal margin concave, proximally raised, elongate escutcheon outlined by dorsal carina; hinge elongate, moderately broad, large, acute chevron-shaped teeth up to 16 in anterior series and up to 28 in posterior series, anterior series extends to anterior limit of anterior adductor muscle, posterior series extends approximately half length of postero-dorsal margin to anterior limit 129 of posterior adductor muscle, ventral margin of hinge plate corre- sponds to line of dorsal carina, ventral to umbo teeth approach shell margin, anterior and posterior hinge plates continuous; ligament internal, ventral to umbo and close to shell margin, slightly inclined posteriorly; rounded internal ridge extends from umbo to posterior margin. The maximum recorded shell length is The prodissoconch is very large and measuring 560um in length.
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Photo credit: © Book Worm / Alamy / Afripics
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Keywords: ., bhlconsortium, bookcentury1900, bookcollectionbiodiversity, bookl
