Nature of phenomenon, arhythmic, hyperexcitability of nerve centres or skin. Nerve section. Head jerking: =horse=, hard bit, severe check, internal pain, exertion, hypersensitiveness. Treatment: nerve section. Tongue lolling, etc. Flapping of lower lip. Nasal rhythmic movements. Weaving, from impatience, rhythmic. Rocking on hind limbs. Resting foot on coronet. Pawing. Treatment: eliminate irritation, nerve tonics, sedatives, hygienic measures. This has been observed especially in the dog and may be easily confounded with chorea. The muscles on one side of the face, are twitched at more or less regular intervals, or in other cases there are sudden opening and closing of the lower jaw. The affection has not been satisfactorily connected with any special brain lesion, though as in chorea proper and epilepsy, we must invoke a special disorder or hyperexcitability of the nerve centres presiding over the affected muscles. The clonic spasm may in some cases be due only to a motor impulse from such excited nerve centre, while in others it may be traced backward along the afferent nerves to an oversensitive part of the skin or other organ. In these last purely reflex forms of the trouble it may be possible to correct it by section of the sensory nerves involved. Convulsive Movements of the Head. Convulsive movements of the head as a whole constitute a frequent form of chorea in the dog. It is especially common in horses and shows itself in different forms. A horse with a tender mouth, or which has been used with a hard bit, or with a heavy hand on the reins, or which has been driven with a check rein so short as to be unsuited to its conformation, is liable to indulge in annoying elevation and depression of the head when under the saddle or in harness. The same phenomenon may be shown in connection with violent internal pains, as in strangulated hernia, intussusception, or twisting of the bowels. The habit once formed is not easily corrected, so that careful treatment with the view of prevention is especially to be given.