27 relations to the other parts of the right ven- tricle in this bird which the band so named by Mr. T. W. King in the Guy's Hospital Reports, vol. ii. p. 122, 1837, holds in many, if not in all, Ungulate mammals. This, I presume, is made plain by a comparison of the two diagrams (Figures 2 and 3) show- ing, one of them the heart of this bird, the other the heart of a sheep, with the right ventricle similarly laid open in each case. The advantage, which in the struggle for existence, and specially in that very com- mon phase of it which takes the form of a race for food or from an eater, which an animal with such a muscular band passing directly across the cavity of its right ven- tricle from its fixed to its movable wall must possess, is not a difficult thing for any man to understand who has ever either watched in another or experienced in himself the dis- tress caused by the over-distension of any muscular sac f . A band of similar function f Since writing as above I have been reminded of what I ought not to have forgotten, viz. that my friend Dr. Milner Fothergill has discussed this very subject in his work, The Heart and its Diseases with their Treatment, London. 1872, p. 6.