| OCR Text |
Show 480 PROF, LANKESTER ON THE HEART OF APTERYX. [May 5, Heart of Ornithorhynchus. The right ventricle opened so as to expose the right cardiac valve. There is no connection here of the great anterior muscular band (a) of the valve with the free wall of the ventricle. It arises entirely from the septal wall. The distinction is not a fundamental one; the muscular band a in figs. 5 and 6 is to be identified with the muscular band a of the Birds' hearts (figs. 1 to 4). Similarly the much shorter muscular band or ibid c in the Birds' hearts appears to be the same structure as the band marked c in the present figure of the right cardiac valve of Ornithorhynchus. Fig. 6. The same heart as that drawn in fig. 5, with the great anterior muscular band (a) cut through, so as to allow the valve to be reflected, for comparison with the similar views of the heart of the Fowl, fig. 2, and the heart of Apteryx, fig. 4. Letters in all the figures. a. The large anterior muscular band passing from the free margin of the valvular flap to the ventricular wall (this is the great anterior musculus papillaris of Mammals), b. The muscular flap of the Birds' valve, c. The small left muscular band of attachment from the valve to the ventricular wall (lelt or " conus " musculus papillaris of the Mammal). |
