The Nautilus . 11),slightly inequilateral, beaks subcentral, not prominent(Figures 2-4). Anterior end rounded and slightly pro-jecting, posterior end truncate (less markedly in juve-niles), slightly oblique (Figures 4, 5). Dorsal marginstraight or slightly and evenly arcuate, posterior marginstraight, ventral margin slightly and evenly curved,crenulate. Valves gaping ventrally and at anterior andposterior ends (Figures 8-10). Nepionic shell (approx-imately 470 (xm length), inflated, forming a roundedcup (Figure 11), clearly demarcated by a commarginalrim (Figure 12). Shell surface sculptured w
The Nautilus . 11),slightly inequilateral, beaks subcentral, not prominent(Figures 2-4). Anterior end rounded and slightly pro-jecting, posterior end truncate (less markedly in juve-niles), slightly oblique (Figures 4, 5). Dorsal marginstraight or slightly and evenly arcuate, posterior marginstraight, ventral margin slightly and evenly curved,crenulate. Valves gaping ventrally and at anterior andposterior ends (Figures 8-10). Nepionic shell (approx-imately 470 (xm length), inflated, forming a roundedcup (Figure 11), clearly demarcated by a commarginalrim (Figure 12). Shell surface sculptured with 30-35relatively well-marked radial ribs and irregular com-marginal ribs, both fading towards the beaks. Radialribs often very evident in small-sized specimens, tend-ing to fade in adults. Hinge edentulous in adults. Lig-ament internal, strong; external periostracal ligamentpresent (Figures 13-16). D-shaped larvae with two well-developed lamellar lat-eral teeth in the right valve, the anterior long and slen-. Figures 2-3. Waldo parasiticus. Leetotype, USNM 11907. 2. Right lateral view. 3. Posterolateral view showing the exhalantsiphon and the unpaired tentacle above the siphon, f: foot; s: siphon; t: tentacle. Scale bars = 1 mm. D. G. Zelaya and C. Ituarte, 2002 Page 111
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectmollusks, bookyear188
