Monography of the family Unionidæ : or, Naiades of Lamarck (fresh water bivalve shells) of North America ... . e upper part of theumbonial slope. The sinus of the cartilage is muchshorter than in the variety of the allied species whichit most nearly resembles, (U. cariniferns, Lam.) theposterior margin more oblique, and the umbo is muchwider; it has also more robust and much less promi-nent cardinal teeth; a much smoother and lesswrinkled epidermis, and the interior is never darkpurple. UNIO ANGUSTATUS. Plate LIV.—Fig. Shell elliptical, elongated, ventricose; disks slightlycontr
Monography of the family Unionidæ : or, Naiades of Lamarck (fresh water bivalve shells) of North America ... . e upper part of theumbonial slope. The sinus of the cartilage is muchshorter than in the variety of the allied species whichit most nearly resembles, (U. cariniferns, Lam.) theposterior margin more oblique, and the umbo is muchwider; it has also more robust and much less promi-nent cardinal teeth; a much smoother and lesswrinkled epidermis, and the interior is never darkpurple. UNIO ANGUSTATUS. Plate LIV.—Fig. Shell elliptical, elongated, ventricose; disks slightlycontracted obliquely from beak to base; ligament andbasal margins parallel; anterior dorsal margin ele-vated, obtusely rounded at tip; posterior marginrectilinear, profoundly oblique; extremity obliquelytruncated, the inferior angle or tip acute; considera-bly above the line of the base; umbonial slope angu-lated, rectilinear; beaks decorticated, slightly promi-nent, acute, approximate; basal margin slightlycontracted in the middle, epidermis brown olivaceous,obscurely rayed; within pale chocolate colour and.
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Keywords: ., bookcentury1800, bookdecade183, booksubjectmollusks, bookyear1836
