6. Make a list of all the vertebrate animals with which you are acquainted. Why are they called vertebrates?
7. By what external characters would you recognise that an animal was a mammal?
CHAPTER XIII.
HOW A RABBIT LIVES.
44. THE SKELETON AND MUSCLES
1. The examination of the bones.—In a boiled rabbit clear away the flesh from the bones. Before separating a bone, notice carefully how it is attached to neighbouring bones. Notice also, especially in the limbs, the attachment of the bundles of flesh (muscles) to the bones, the ends of each muscle being fixed to separate bones. Notice that the places of attachment of the largest muscles are marked by ridges or roughnesses on the bones.
2. The skull.—Observe the two rounded knobs at the back of the skull, which fit into hollows on the first bone (vertebra) of the vertebral column. In the skull notice the saw-like boundaries of the various bones, and make out: the great, rounded brain-case; the external openings of the ears; the eye-sockets; the snout, with the two nasal chambers; and the upper and lower jaws. Before separating the lower jaw observe carefully how it is hinged on the arches which run below the eyes, and notice the great muscle on each side which moves it. Examine the teeth in detail, and remove them one by one from their sockets. Notice the bony shelf or palate separating the nasal chambers from the cavity of the mouth. Draw a side view of the skull.
Shave off the top of the brain-case with a sharp knife, and examine the brain.
3. The vertebral column.—Make out that each of the bones (vertebrae) which compose the vertebral column is really a ring, and that the whole column is therefore a bony tube. In this tube is enclosed the spinal cord, a backward continuation of the brain. Examine and draw vertebrae from the various parts of the column, and notice how they vary in shape and size. Compare vertebrae from (a) the neck, (b) the region of the chest (notice the attachment of the ribs), (c) the abdominal region, (d) the region of the hips (four united vertebrae; leave these for the present in position between the hip-bones), (e) the tail.