. Bulletins of American paleontology. eKi^--':^. Text-figure 16. — Position of nodes in the Cyprideidini. A = anterior AD = anterodorsal (in front of sulcus) D = dorsal PD = posterodorsal P = posterior V =r ventral Numbered circles indicate node positions. hardly visible; anterior groups: ventral group (A 1) as continuation of the ventral row, middle group (A 2), consisting of two of the tubercles slightly behind the other two rows and a very irregular group of tubercles (A3), varying from 5 tubercles in a single row to many in triple rows. A deep sulcus separates the dorsal and antero- dorsal
. Bulletins of American paleontology. eKi^--':^. Text-figure 16. — Position of nodes in the Cyprideidini. A = anterior AD = anterodorsal (in front of sulcus) D = dorsal PD = posterodorsal P = posterior V =r ventral Numbered circles indicate node positions. hardly visible; anterior groups: ventral group (A 1) as continuation of the ventral row, middle group (A 2), consisting of two of the tubercles slightly behind the other two rows and a very irregular group of tubercles (A3), varying from 5 tubercles in a single row to many in triple rows. A deep sulcus separates the dorsal and antero- dorsal nodes, passes behind the central node, ends just above the anterior tubercle of the ventral row, and contains on the inside the adductor muscle-scars. The marginal area is broad; radial pore canals are long, often branching, and they emerge in the spacings between the minute, flattened teeth on the anterior margin. Hinge holomerodont, con- sisting in the right valve of an elongate dental area with about 10 heart-shaped cusps, a posterior dental area with about 6 cusps, and a finely crenulate ridge in between. Adductor muscle-scars con- sist of a vertical row of four scars of which the top two are slightly elongate and oblique. In front of the uppermost scar is a fulcral scar and a single frontal scar, which appears to be heart-shaped. In front of and ventral to the adductor scars, and vertically below the frontal scar, is a single, elongate mandibular Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Paleontological Research Institution (Ithaca, N. Y. ); Columbia University. Ithaca, N. Y. , Paleontological Research Institution [etc. ]
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