. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. 100 Mr. M. C. March on the Anterior to tlie ligament:— LA I, LA TU, LA V, for the riolit valve. LA II, LA IV, LA VI, for the left valve. Posterior to tlie ligament :— LP I, LP III, LP V, for the right valve. LP II, LP IV, LP VI, for the left valve. The posterior ends of these lamelloe bend round so as to He more or less perpendicular to the hinge-line, and may become differentiated from the anterior part. The posterior portions form ihe cardinals, the anterior jiortions form t
. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. 100 Mr. M. C. March on the Anterior to tlie ligament:— LA I, LA TU, LA V, for the riolit valve. LA II, LA IV, LA VI, for the left valve. Posterior to tlie ligament :— LP I, LP III, LP V, for the right valve. LP II, LP IV, LP VI, for the left valve. The posterior ends of these lamelloe bend round so as to He more or less perpendicular to the hinge-line, and may become differentiated from the anterior part. The posterior portions form ihe cardinals, the anterior jiortions form the lateral teeth or remain as unditfercntiated lamellae. The posterior himellai are unaltered except in the case of Condylo- cardia (fig. 7). The anterior cardinals may become bifurcated forming anterior portions. rig. 7. CAZ. VoKh/hcardia crassicosta (after Bernard), showing the occuiTeuce of posterior cardinals. 1. Left valve. 2. Pight valve. The reduction of the heterodont hinge to a scheme, and the cursory comparison of that scheme with the actual adult heterodont hinge, makes the conception seem too simple to be really possible. It is only by carefully follov\'ing out Bernard^s papers, and by the comparison of his descriptions of the adult shells with the actual specimens that it becomes clear that the hinges do develop on that plan. In actual practice Y appears rarely, ami YI very 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 London, Taylor and Francis, Ltd
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