. Beginners zoology. Zoology. MAMMALS 189 The skull is joined to the spinal cokinin by two knobs (or condyls), which fit into sockets in the first vertebra. Compare the jaws with those of a bird and a reptile. There is a prominent ridge in the temple to which the powerful chewing muscles are attached. There is also a ridge at the back of the head where the muscles which support the head are attached (Fig. 348). Count the ribs. Are there more or fewer than in man .'' The breastbone is in a number of parts, joined, like the vertebrae, by cartilages. Compare it with a bird's ster- num ; why the d
. Beginners zoology. Zoology. MAMMALS 189 The skull is joined to the spinal cokinin by two knobs (or condyls), which fit into sockets in the first vertebra. Compare the jaws with those of a bird and a reptile. There is a prominent ridge in the temple to which the powerful chewing muscles are attached. There is also a ridge at the back of the head where the muscles which support the head are attached (Fig. 348). Count the ribs. Are there more or fewer than in man .'' The breastbone is in a number of parts, joined, like the vertebrae, by cartilages. Compare it with a bird's ster- num ; why the difference .-' The shoulder girdle, by which the front legs are attached to the trunk, is hardly to be called a gir- dle, as the collar bones (clavicles) are rudimentary. (They often es- cape notice during dissection, being hidden by muscles.) The shoulder blades, the other bones of this gir- dle, are large, but relatively not so ^'"l; ^^'- " "rt^'" "^ ^^l ° -' (i) retracted by ligament, and broad toward the dorsal edge as (2) drawn down by muscle hi 11 ui J T-u 1 attached to lower tendon, uman shoulder blades. 1 he clav- icles are tiny because they are useless. Why does the cat not need as movable a shoulder as a man ? The pelvic, or hip girdle, to which the hind legs are attached, is a rigid girdle, completed above by the spinal column, to which it is immovably joined. Thus the powerful hind legs are joined to the most rigid portion of the trunk. Mammals.— The cat belongs to the class Mammalia or mammals. The characteristics of the class are that the young are not hatched from eggs, but are born alive, and nourished with milk (hence have lips), and the skin is covered with hair. The milk glands are situated ventrally. The position of the class in the animal kingdom was. 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
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1921
