. Elements of conchology / Prepared for the use of schools and colleges. Mollusks. PARTS OF BIVALVE SHELLS. in contact with the corresponding part of th€ opposite valve, it is " irregular," or emarginate. Besides the parts mentioned, we shall find in most cas-es, an- terior to the apices of the beaks, a depression of variable extent and depth. This is the lunule {fig. 118, I) I it may be cordi- forna, or crescentic, lanceolate (oblong, and gradually tapering towards each extremity), oval, deep, superficial, &c. Behind the beaks is another depression, longer and narrower than the
. Elements of conchology / Prepared for the use of schools and colleges. Mollusks. PARTS OF BIVALVE SHELLS. in contact with the corresponding part of th€ opposite valve, it is " irregular," or emarginate. Besides the parts mentioned, we shall find in most cas-es, an- terior to the apices of the beaks, a depression of variable extent and depth. This is the lunule {fig. 118, I) I it may be cordi- forna, or crescentic, lanceolate (oblong, and gradually tapering towards each extremity), oval, deep, superficial, &c. Behind the beaks is another depression, longer and narrower than the lunule, and which is called the fissure (/), and its margins are named lips of the fissure (If). Behind tlie fissure there is sometimes a small depression called the suture (s). The general more or less convex surface of each valve is called the ^' venter," or belly, which terminates in the limb^ circum- ference or margin. In the figure (118), the letters designate parts, as follows: A, anterior slope; P, posterior slope; L, left valve; R, right valve; /, lunule;/! fissure; Z/', lips of the fis- sure ; 5, suture; lig^ ligament; ny, the nymphse. • /LICANIEKT-, \ ' / NVMPHAEv \ \. Fig. 118.—CYTHEREA,. 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 Ruschenberger, W. S. W. (William Samuel Waithman), 1807-1895; Comté, Achille, 1802-1866; Milne-Edwards, H. (Henri), 1800-1885. Philadelphia : Grigg & Elliot
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectmollusks, bookyear184
