Ribs (Costae), in the human frame, are certain long bones of a semicircular figure. There are twenty-four in number, namely, twelve on each side the twelve vertebrae of the back, or the spinal column. They are divided into se-ven true, which are uppermost, and five spurious, or false ribs, which are softer and shorter ; only the first of the latter being joined to the extremity of the breast-bone, while the gristly ends of the rest are combined with each other, and thus leave a greater space for the dilatation of the stomach and bowels. It is farther remarkable, that the cartilages through out the ribs, are harder in the female than in the male subject, obviously with the view of enabling the former to support more easily the weight of their breasts ;- that the last of the false ribs is perceptibly shorter than the rest, and is not joined to them, but in some persons to the oblique descending muscle;- that Nature has providently not constructed the ribs like the other solid, articulated bones; in order to admit of such a degree of expansion in the thorax or chest as is requisite to perform the important process of breathing. Hence, if in an easy inspiration the cavity of the thorax is raised 1 - 8th of an inch, and the midriff descends only 1 1/2 inches, it will afford room for 52 cubic inches of air to enter ; so that, in an ordinary inspiration, the lungs are distended with70, and sometimes 100, inches of atmospheric air.- Lastly, theribs serve to defend the vital organs, and to impart adhesion to the muscles.

The principal casualties incident to the ribs, are fractures, and luxa-tions. The former may be easily ascertained, on pressure with the fingers. The symptoms are sel-dom accompanied with aggravating circumstances, and the patient speedily recovers. If, however, the fracture be compound, or the bone depressed on the lungs, a very acute pain will be felt ; breathing become difficult; and be attended with cough, sometimes with blood-spitting ; while a full and quick pulse will indicate the presence of fe-ver.—Li such cases, it will always roper immediately to apply for surgical assistance, and perhaps to lose a few ounces of blood. If one end of the rib be elevated, it ough to be reduced by moderate compression ; and a broad leather belt constantly be worn tightly around, for several weeks. Should any part of the rib be forced inwards, it must be carefully raised by the surgeon ; and, if any air or extravasated blood be collected in the cavity of the chest, these fluids are to be timely and cautiously extracted.

Luxations of the ribs seldom oc-cur. The svmptoms correspond with those attending fractures, ex-cepting that the pain is more acute at the articulation, which part alone will yield on pressure. In case, the patient's body should be slowly bent over a cask, or a round vessel, in order to expand the ribs, and thus to reduce the luxated bone ; as no bandages will afford any relief.- In all accidents of this nature, however, the patient ought to be kept on low and cooling diet; to avoid •whatever may tend to irritate or disturb his mind, lest inflammation might ensue and, if the cough be troublesome, it will be advisable to employ opiates (especially by means of unguents externally), with a view to allay its virulence.