 | Academy of Natural Sciences of Philadelphia - 1834 - 482 páginas
...two of which are on the basal margin, extending nearly its entire length; anterior side gibbous, with the concentric lines lamellar, crowded, undulated, and crossed by numerous impressed lines ; valves much contracted submedially, with an oblique groove ; umbonial slope angulated ; posterior... | |
 | Ida Shepard Oldroyd - 1924 - 390 páginas
...two of which are on the basal margin, extending nearly its entire length; anterior side gibbous, with the concentric lines lamellar, crowded, undulated and crossed by numerous impressed lines ; valves much contracted sub-medially, with an oblique groove ; umbonal slope angulated ; posterior... | |
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Phila., 7:236; pl. 18, fig. 5. Shell elongated, with eight accessory valves, two of which are on the basal margin, extending nearly its entire length; anterior side gibbous, with the concentric lines lamellar, crowded, undulated and crossed by numerous... 