Monography of the family Unionidæ : or, Naiades of Lamarck (fresh water bivalve shells) of North America ... . esented in the figure. A spi-nous Unio, no doubt the same species, is said tooccur abundantly near Columbia in South is a smaller species, less pointed posteriorly,and otherwise distinct from the U. spinosus of Lea. UNIO TRABALIS. Plate LX.—Fig. 2. DESCRIPTION. Shell oblong-ovate, ventricose, thick anteriorly;anterior side short, margin obtusely rounded; poste-rior side cuneiform, produced, obtusely rounded atthe extremity, which is narrow; hinge margin decli-ning; poste
Monography of the family Unionidæ : or, Naiades of Lamarck (fresh water bivalve shells) of North America ... . esented in the figure. A spi-nous Unio, no doubt the same species, is said tooccur abundantly near Columbia in South is a smaller species, less pointed posteriorly,and otherwise distinct from the U. spinosus of Lea. UNIO TRABALIS. Plate LX.—Fig. 2. DESCRIPTION. Shell oblong-ovate, ventricose, thick anteriorly;anterior side short, margin obtusely rounded; poste-rior side cuneiform, produced, obtusely rounded atthe extremity, which is narrow; hinge margin decli-ning; posterior margin slightly contracted just abovethe extremity of the valve; umbonial slope rounded;posterior slope flattened or concave, in old shellsfurrowed; beaks eroded and rather prominent; basalmargin arched; epidermis smooth and polished, darkolive-brown tinted with green, and with dark greenunequal rays, not very distinct; within dull white orslightly salmon-coloured anteriorly; bluish and veryiridescent posteriorly; cardinal tooth in the rightvalve very thick and direct, in the left valve the car- 60.
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Keywords: ., bookcentury1800, bookdecade183, booksubjectmollusks, bookyear1836
