. Elements of zoölogy. Zoology. 294 BACKBONED ANIMALS. Class VII.—Mammalia {Milk-givers). General Characteristics.—We now come to the highest and most perfect animal forms. They are covered with hair instead of scales. The young are born alive,* and nourished by a fluid called milk, secreted in the mammary glands. About twenty-one hundred species of living mammals are known, three hundred and ten inhabiting North America. Skeleton.—The skeleton, that in the majority of birds is extremely light, is in the mammals solid, and the limb- cavities filled with marrow. Taking the cat (Fig. 321) as an
. Elements of zoölogy. Zoology. 294 BACKBONED ANIMALS. Class VII.—Mammalia {Milk-givers). General Characteristics.—We now come to the highest and most perfect animal forms. They are covered with hair instead of scales. The young are born alive,* and nourished by a fluid called milk, secreted in the mammary glands. About twenty-one hundred species of living mammals are known, three hundred and ten inhabiting North America. Skeleton.—The skeleton, that in the majority of birds is extremely light, is in the mammals solid, and the limb- cavities filled with marrow. Taking the cat (Fig. 321) as an example, we first note the cranium, era, or skull, that is united to the backbone or vertebral column by two occipital con- dyles. The lower jaw is composed of two pieces, and is joined directly to the skull, and not to the quad- rate bone, as we have seen in the birds and reptiles. The back- bone is divided into five divisions : First, the cervical or neck region, where the vertebrae generally number seven. In the cat they are small, in the whale they are pressed together, while in the long-necked giraffe each bone is lengthened out. Sec- ond, the dorsal or back region, the vertebrae of which generally number from ten to fifteen ; they support the. 7 89654 Fig. 321.—Cat, with bones of right side drawn. Cra, cranium ; sc, scapula or shoulder- blade ; 1, humerus ; 2, radius and ulna ; 3, carpus ; 4, phalanges ; 5, femur ; 6, tibia and fibula; 7, tarsus ; 8, metatarsus; 9, phalanges ; /, innominate bone, a number of bones combined, forming the pelvic arch ; v, vertebral column. (After Morse.) * See note on page 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 Holder, Charles Frederick, 1851-1915; Holder, Joseph Bassett, 1824-1888, joint author. New York : D. Appleton and company
Size: 1890px × 1322px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
