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Venerupis galactites (Lamarck, 1818), an endemic Australian infauna! venerid clam, is morphologically/ anatomically described based on specimens collected in shallow-water Posidonia australis seagrass beds in Esperance Bay, Western Australia. The species lives in high densities (1 ,300/m2) in 2-4 cm sediment depth, byssally attached to the seagrass rhizome mats. Notable features of its anatomy include elongated siphons that are united nearly to the tip, expansive plicated gills, and a prominent byssal groove on the posteroventral foot. The byssal gland in histological sections is irregularly ovoid and cupulate, with a narrow lumen; the microfibrillar ribbon-like byssus forms a single thick proximal stalk that divides distally into 2- 3 branches. Each branch can have numerous periodic, flat and parallel side-branches that extend from one side of the primary byssal thread and terminate in attachment plaques. The form of the byssus is reflected in the byssal duct, which has an infolded secretory epithelium that forms or molds the side branches. Byssal attachment by adult clams is discussed for the largely free-living and infauna! family Veneridae, a group in which neotenous retention of this postlarval feature was thought to be restricted to intertidal rock nestlers. Rather than representing a simple retention of neotenous features, the elaborate byssal apparatus of V galactites is clearly derived. The parallel side branches seen along a single side of the primary byssal threads could reflect an adaptive feature for secure adhesion in an infaunal life mode nestled along relatively narrow, cylindrical rhizomes.