. Bulletin of the Natural History Museum Zoology. DEEP-SEA PROTOBRANCHIA (BIVALVIA) 117. Fig. 23. Ledella aberrata. Siphonal region, as seen from the inside of the mantle cavity. See abbreviations to the text-figures p. 102. Scale = This species occurs at upper to mid slope depths in the tropical western Atlantic in the Brazil, Guyana, Caribbean and Gulf of Mexico Basins (Dall, 1889; James 1972). Depth range; 943-2500m. The holotype for T. agatheda was not designated by Dall (1890), nevertheless he did illustrate the left valve from Albatross Sta. 2754, 11°40'N 58"33'W (USNM 95437)
. Bulletin of the Natural History Museum Zoology. DEEP-SEA PROTOBRANCHIA (BIVALVIA) 117. Fig. 23. Ledella aberrata. Siphonal region, as seen from the inside of the mantle cavity. See abbreviations to the text-figures p. 102. Scale = This species occurs at upper to mid slope depths in the tropical western Atlantic in the Brazil, Guyana, Caribbean and Gulf of Mexico Basins (Dall, 1889; James 1972). Depth range; 943-2500m. The holotype for T. agatheda was not designated by Dall (1890), nevertheless he did illustrate the left valve from Albatross Sta. 2754, 11°40'N 58"33'W (USNM 95437) which we have here nominated as lectotype. We have redrawn the shell and added detail of the hinge plate (Figs 24 and 25). In addition, James (1972) reported that two valves of T. agathedawere included in USNM 63149 from Blake sta. 236, 2909m off Bequia, furthermore USNM 94326 from Blake stas 26 and 30 between Cuba and Yucatan, identified by Dall as Leda pusio, are examples of T. agatheda. Shell description (Figs 24 & 25) Shell small, sub-ovate, wide, sub-rostrate, ornamented with con- centric ridges, postero-lateral furrow ventral to sub-rostrum, ill-defined lunule outlined by obscure ridge, escutcheon similarly ill-defined and bounded by faint ridge; umbo prominant, poste- rior to mid-line, inwardly directed; antero-dorsal margin concave, with change in slope at anterior limit of hinge plate, slightly flattened anteriorly dorsal to the anterior limit of shell, antero- ventral and ventral margins smoothly curved, postero-ventral margin slightly sinuate, posterior margin acutely angled, postero- dorsal margin slightly concave, marked angle at posterior limit of hinge plate and thereafter almost straight to form sub-rostrate posterior margin; anterior and posterior limits of shell are ventral to horizontal mid-line; hinge plate strong, with edentulous space ventral to umbo, hinge teeth stout, chevron-shaped, up to 12 in each series in shell 6mm total length; internal ligam
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Keywords: ., bhlconsortium, bookcentury1900, bookcollectionbiodiversity, bookl
