This little animal is common in Brazil where it lives on trees and secures itself by means of its hind-feet, it uses its tail, which is pretty long, as a means of descending. Its length, from the muzzle to the tip of the tail, is about a foot; the tail is almost as long as the trunk. The upper parts of the body are covered with sharp prickles about an inch and a half long, and attached to the skin by means of a very thin pedicle. The head-prickles are white at the base, black in the middle and of a yellowish-brown at the top, the dorsal prickles are of a sulphur-yellow at their base. The prickles on the rump and the first third of the tail, are black at their extremity. All the prickles are very close together, mingled with a few long and fine hairs. The lower limbs are covered with a grayish fur, interspersed with little prickles; the tail is furnished with prickles at its upper part, and is covered with stiff and black hairs; the extremity of the tail is bare. We triturate the prickles taken from one of the sides. Prover: _Jo. Vincente Martins._ _First day._—Took one dose of the third trituration at 8 in the morning. 1. Desire to vomit and nausea at the sight of food, immediately. At night, sense of dryness and fullness in the stomach. Very drowsy after dinner. _Second day._—5. Wakes early. Merry and quiet dreams. Sense of fullness in the abdomen, at 5 in the morning, when lying. Diarrhœa. Transitory pains in the toes, right temple and one of the right cuspidati. 10. Pains at the lower extremity of the right forearm. Pain at the right zygoma. Pain at the first incisor. Bleeding of the gums. Pain in one half of the head. 15. Buzzing in the ears. The knees give way, likewise the tarsal joints. The toothache becomes obstinate. After dinner all the pains cease. Shuddering with chattering of the teeth. 20. Cough with pains in the chest. Stitch in the region of the heart, left side, which stops his speech for two minutes. Pain at the right arm, from the hand to the elbow, as if extending the arm were prevented by a string. Improvement when turning the arm or lifting a weight, or moving it about; aggravation as soon as these movements cease. After breakfast, boring pain through the bones of the skull. 25. Aggravation when lying down, and improvement when walking in the open air. Pains in the stomach, as if strung together.