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in pathological or clinical observation — viz. that the auricles may remain extremely distended for hours, and, like other mus- cular sacs similarly conditioned, unable to contract and empty themselves, without the circulation for all that being brought to a standstill. It was Dr. Pavy's paper, treat- ing (in the Medical Times and Gazette of November 21, 1857) of the case of a man (E. Groux) with a congenital fissure of the sternum, which first drew my attention to these points ; and his summary of what takes place in the dog is so clear that I herewith reproduce it. ' In the dog, the contraction of the ven- tricl es is sharp and rapid, instead of p ro- longed, as in the reptile, and does not app ear to occupy ne arly so much time as half the period of the heart's action. Thj> ventricular contraction communicates a sudden impulse to the auricles, occasioning in them a dis- tinct pulsation, which is instantly followed by a peculiar thrill, wave, or vermicular movement, running through the auricular parietes down towards the ventricle. This thrill or wave is coincident with the passage