A. Skull:—

  1. Cranium, or brain case, the central and hinder portion.
  2. Nasal bone, a triangular bone lying in front of each large opening, or eye orbit, and attached to the anterior end of the cranium.
  3. Premaxillaries, a pair of small bones which form the tip of the nose.
  4. Maxillary, a slender bone forming the side of the upper jaw.
  5. Dentary, the bone of the lower jaw, corresponding to the maxillary.
  6. Occipital foramen, the posterior opening or entrance into the cranium, normally covered dorsally by cartilage and most easily seen in a separate skull.

B. Vertebral Column:—

  1. Cervical vertebra, the first vertebra, supporting the skull.
  2. Dorso-lumbar vertebræ, vertebræ with small lateral processes.
  3. Sacrum, the ninth vertebra, bearing extra long lateral processes or "arms."
  4. Urostyle, the last vertebra, lying in the median line, a long, slender, blade-like bone, really formed by the fusion of several vertebræ.

C. Vertebra:—

  1. Centrum, the solid, nearly circular portion.
  2. Lateral process, one of the paired projections, extending outward on either side.
  3. Neural spine, the single projection, extending toward the dorsal side.
  4. Neural arch, formed largely by a connection between the lateral process and the neural spine. The arch above and the centrum below inclose the neural canal.

D. Pectoral, or Shoulder, Girdle:—

  1. Sternum, the "breastbone," extending along the median ventral line.
  2. Coracoid, a heavy bone extending from the sternum sidewise to support the arm.
  3. Clavicle, the "collar bone," a light bone in front of the coracoid.
  4. Scapula, the "shoulder blade," a broad, thin bone which arches around to the dorsal side.

E. Pelvic, or Hip, Girdle:—

  1. Ilium, a long, slender, curved bone, with its mate uniting to form an inverted "wishbone"; it is joined to the sacrum.
  2. Pelvis, the region of the socket at the junction of the ilia.