Bulletins of American paleontology . f lying flat against it. Bifurcated denticles and a labial spineare common on the outer lip, transverse wrinkles being developedon the slightly flexed pillar. Reddish bro^vn spiral color bandsparallel costae or rows of coarse tubercles and numerous finer in-terstitial threads. Varices are two per whorl, discontinuous butmore or less in lateral positions. The light or dark brown perio-stracum is thick and velvety; it is generally eroded away from theapex. This species attains the largest size of any Argohuccinum;adults have seven or more whorls and range up
Bulletins of American paleontology . f lying flat against it. Bifurcated denticles and a labial spineare common on the outer lip, transverse wrinkles being developedon the slightly flexed pillar. Reddish bro^vn spiral color bandsparallel costae or rows of coarse tubercles and numerous finer in-terstitial threads. Varices are two per whorl, discontinuous butmore or less in lateral positions. The light or dark brown perio-stracum is thick and velvety; it is generally eroded away from theapex. This species attains the largest size of any Argohuccinum;adults have seven or more whorls and range up to cm high. Variahility.—As in A. argus and A. ranelliforme the speciesfrom New Zealand and Australia has several variable characters. Cymatiid Gastropods: Smith 471 Juveniles and young adults may not exhibit the normal tumidity,and these forms are not easily separable from young specimens ofA. ranelliforme. Such morphologic evidence of the close relation-ship of these species, together witli other shell characters, led Dell. VAN DIEMEN 500 1000 1500 2000 Kf RECENT UPPER PLEISTOCENE Text-figure 7. — Distribution of Argobuccinum tumidum (Dunicer). 472 Bulletin 254 (1963) to identify the New Zealand material as a subspecies ofA. ranelliforme. This classification is not followed here becausethere may be other forms, stich as variants of A. argiis and A. pro-ditor, to which A. tumidum may be more immediately related. Both A. ranelliforme and A. tmuidum may have slender, bead-ed late juvenile forms, and large, mature shells with inflatedwhorls. The combination of timiid outline, pillar callotis and de-tails of spiral sculpture distinguish the western Pacific from theSouth American species. Adult sculpture varies from smooth spiral costae to rows oftiny beads to irregular nodes. Specimens having large, irregularlyspaced tubercles are reminiscent of typical forms of A. argus, whilethose having regular patterns look more like A. ranelliforme. Ma-jor spirals in A. tumidum are
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