. An introduction to the osteology of the mammalia . FIG. 41 —Sternum of Rudolphis Whale {Balcen&ptera borealis), showing its relationto the inferior extremities of the first pair of ribs. From Proceedings ZoologicalSociety, 1883. In the SIRENIA the sternum is a simple, flattened, some-what elongated bone, which in the adult shows no trace FIG. 42.—Sternum of a young Dugong (Halicore indicus), \. From a specimen in the Leyden Museum. In a young Dugong (Halicore), Fig. 42, there are twodistinct ossifications,—a presternum (ps), to which the first 102 THE STERNUM. [CHAP. pair of
. An introduction to the osteology of the mammalia . FIG. 41 —Sternum of Rudolphis Whale {Balcen&ptera borealis), showing its relationto the inferior extremities of the first pair of ribs. From Proceedings ZoologicalSociety, 1883. In the SIRENIA the sternum is a simple, flattened, some-what elongated bone, which in the adult shows no trace FIG. 42.—Sternum of a young Dugong (Halicore indicus), \. From a specimen in the Leyden Museum. In a young Dugong (Halicore), Fig. 42, there are twodistinct ossifications,—a presternum (ps), to which the first 102 THE STERNUM. [CHAP. pair of ribs are attached, and a xiphisternum (xs). Thesecond, third, and fourth pairs of sternal ribs are attachedto the intermediate unossified portion, representing a rudi-mentary mesosternum. In the Manatee (Manatus) the sternum is of somewhatsimilar form, and has three pairs of ribs attached to itslateral margins near the middle. Among the EDENTATA there is considerable variation inthe characters of the sternum. In the Cape Anteater (Orycteropus) the sternum is ofquite a normal form. The presternum is trefoil-shaped,expanding laterally near the front to meet the largelydeveloped clavicles, then contracting to the width of themesosternal segments, which are four in number, simple,flattened, oblong, with lateral margins nearly parallel,rather broad
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbones, bookyear1885
