29. _The indications of age_ are no less deserving of notice. The edges of the lower jaw become sharp, and ultimately retracted; the cheeks grow flat; the membrane of the mouth loses its vascularity, and puts on a dull yellowish colour; the gums look hard, and the front of the jaw becomes narrower, while at the same time it inclines more backward, causing the teeth to project horizontally. The inclination which age gives to the teeth, will be easily perceived by comparing the coloured engravings with each other; and the peculiarity of the upper and lower incisors not being perceptible at the same time in the mouth of a thirty-years old, entirely springs from the acuteness of the angle which they form at that period. The bars, as years accumulate, also change their positions, being drawn upwards. From the space between the corner incisors and the first molars, the tongue on either side protrudes, as if the narrowed cavity left not sufficient room for the organ to repose in. The extent to which the tongue will project may be conjectured, by regarding the representation of it given in the coloured plate of the thirty-year old mouth. At that age, the protrusion is too strongly marked to escape the observation of any one whose attention has once been directed to the circumstance. Accompanying the inability to retain the tongue within the jaws, is a constant flow of saliva, which continually falls from the mouth of the old horse when the lips be held apart. The latter fact, the author, when he made the drawings for the present work, had ample experience of, as in some instances it occasioned serious delay.