. Outlines of zoology. Zoology. 644 MAMMALIA. Associated with the olfactory chambers are the nasals above, the vomers beneath, the mesethmoid in the median line, while internally there are several thin scroll-like turbinal bones. As special characters of the skull should be noted the incomplete ossification of certain of the bones, of the maxilla, and the development of slender rod-like processes from some of them, the squamosal, which help to keep the parts of the skull firmly connected. The lower jaw or mandible consists in adult life of a single bone or ramus on each side, but thi
. Outlines of zoology. Zoology. 644 MAMMALIA. Associated with the olfactory chambers are the nasals above, the vomers beneath, the mesethmoid in the median line, while internally there are several thin scroll-like turbinal bones. As special characters of the skull should be noted the incomplete ossification of certain of the bones, of the maxilla, and the development of slender rod-like processes from some of them, the squamosal, which help to keep the parts of the skull firmly connected. The lower jaw or mandible consists in adult life of a single bone or ramus on each side, but this is formed around Meckel's cartilage from several centres of ossification. Its condyle works on the squamosal. The hyoid lies between the rami of the mandible, in the back of the mouth, and consists of a median "body," and two pairs of horns or cornua ex- tending backwards. The appendicular skeleton consists of the bones of the limbs and the girdles. The pectoral girdle, which supports the fore- limbs, and is itself at- tached by muscles and ligaments to the verte- bral column, virtually consists of one bone— the scapula — on each side. For in all Mam- mals, except Mono- tremes, the coracoid, though a distinct ossifi- cation, forms only a small (epicoracoid) process overhanging the edge of the glenoid cavity in which the head of the humerus works. The last of a distinct metacoracoid is seen in Monotremes, though it may be sometimes re- presented by a small independent ossification on the ventral surface of the glenoid cavity. The clavicle is also much reduced in the rabbit, being only about an inch in length and very slender. It is a membrane bone, and lies in the ligament between the scapula and the sternum. The triangular scapula has a prominent external ridge or spine, continued ventrally into an acromion with a long meta-. Fig. 280.—Rabbit's fore-leg. Sc, Scapula ; cor., coracoid process ; ac, acromion; H., humerus; A'., radius; I/., ulna; C. carpal region;
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Keywords: ., bookauthorth, bookcentury1800, bookdecade1890, booksubjectzoology
