The temperature, or normal heat, of the body of the cat is 100° F. ; it may, however, be slightly above or below this.

Fig. VIII.----Skeleton Of A Cat

A. Cervical or Neck Bones (7 in number). B. Dorsal or Thoracic Bones (13 in number, each bearing a rib). C. Lumbar Pones (7 in number). D. Sacral Bones (3 in number). E. Caudal or Tail Bones (19 to 21 in number).

1. - Cranium, or Skull.

2. - Scapula, or Shoulder-blade.

3. - Clavicle, or Collar-bone.

4. - Humerus.

5. - Sternum, or Breast-bone.

6. - Phalanges of the Toes.

7. - Metacarpal Bones.

8. - Carpal or Wrist-bones.

9. - Radius.

10. - Ulna.

11. - Costal cartilages, uniting ends of Ribs to Sternum.

12, - Patella, or Knee-cap.

13. - Tibia.

14. - Tarsal Bones.

15. - Metatarsal Bones.

16. - Phalanges of Hind Toes.

17. - Heel-bone, or " Calcis."

18. - Fibula.

19. - Femur, or Thigh-bone.

20. - Pelvis, or Hip-bone.

The brain of the cat, following the general structure of the higher mammals, is divided into very similar areas or divisions. The larger or more anterior portion is called the cerebrum (Fig. I., a), and is divided into right and left hemispheres. Its surface is divided into convolutions or gyri (e) by certain shallow fissures, which have received specific names. Very intimately attached to the under-surface of this part of the brain are the olfactory lobes (d), in which are situated certain nerves concerned in the sense of smell. The hinder and smaller part of the brain is called the cerebellum (b), and is much darker in colour than the cerebrum. Its surface is made up of numerous small foldings of its substance, which, on section, look like the branches of a small tree ; these branches finally fuse and terminate on the under-side of the base of the brain.

Fig. I. - Brain Of Cat A, Right hemisphere of cerebrum ; B, Cerebellum; c, Medulla oblongata ; D, Olfactory bulb (nerve of smell) ; E, Convolution, or Gyrus ; F, Fissure.

Intimately associated in a most complex manner with the cerebrum and cerebellum is the medulla oblongata (c), an enlarged part of the spinal cord. The brain of the cat, it may be remarked, is not nearly so highly organised as that of the dog.

In all the higher mammals the eye can accommodate itself to the varying influence of light. This is mainly done by means of the central black part or pupil (Fig. ix., a). The pupil is merely a hole in the iris, or coloured part of the eyeball (b), and it is by its contraction or expansion that the exact amount of light necessary is admitted to act upon the sensitive retina at the back of the eye. The form of the pupil varies considerably in different animals. In the cat's eye during bright sunshine it is reduced to a thin vertical line ; at dusk it expands to a nearly circular form. This vertical reduction is by no means common to the entire cat family. In very many species the pupil retains a rounded form even when contracted to its minimum.

Fig. IX. - The Cat's Eye

At Night-Time.

A. - Expanded And Nearly Circular Pupil.

B. - Iris.

C. - Nictitating membrane.

D. - Opening of Harderian Duct.

C. - Cat's eye, showing the third eyelid or nictitating membrane fully extended.

On the inner angle of the cat's eye there is a curious semi-transparent fold of skin, called by naturalists the plica semilunaris, or nictitating membrane. In reptiles and birds this is a very important factor in the preservation of the eye from external injuries, and it acts also as a regulator of the admission of light. It is well developed in nocturnal reptiles and birds, and as the cat's ancestors were doubtless more nocturnal than they are now, it probably was in active use. It is, however, useless now, the cat having no control over it. It is one of many interesting vestigial structures the cat carries about with it of its former ancestry from a lower-organised animal.

At Day-Time

A. - Contracted linear pupil. B. - Iris. [naris).

C. - Nictitating membrane (Plica semilu-D. - Opening of the Harderian Gland Duct.