. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. PISCES. 989 its margin to the muscular walls shape, but sometimes, as for example in the Sturgeon, resembling the tiicuspid valve of the heart in Mammalia, having chordae tendinese passing from of the ventricle. In other cases again, as in the Sun-fish ( Orthagoriscus Mola), the auricular aperture is guarded by four valves, two small semilunar valves being placed at right angles with and on the auricular side of the two large semilunar valves that usually exist in this situation. The branchial artery (Jig. 522, B) which
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. PISCES. 989 its margin to the muscular walls shape, but sometimes, as for example in the Sturgeon, resembling the tiicuspid valve of the heart in Mammalia, having chordae tendinese passing from of the ventricle. In other cases again, as in the Sun-fish ( Orthagoriscus Mola), the auricular aperture is guarded by four valves, two small semilunar valves being placed at right angles with and on the auricular side of the two large semilunar valves that usually exist in this situation. The branchial artery (Jig. 522, B) which arises from the ventricle is very different in character from an artery of ordinary appearance, its walls being exceedingly thick and muscular, and fre- quently fasciculated internally ; its cavity is more- over dilated so as sometimes to equal in capacity that of the ventricle itself. This dilated portion of the branchial artery, to which the name of Fig. Heart mid principal vessels of Perch, bulbus arteriosus has been given, is in fact almost equivalent to a second ventricular cham- ber, and doubtless by its contractile power forcibly assists in propelling the blood through the gills. The origin of the bulbus arteriosus is always guarded by strong valves, of which there are fre- quently only two of a semilunar form, but occa- sionally the valve is made up of four semilunar membranous folds. But it is not only at the commencement of the bulbus arteriosus that valves exist, these defences being frequently multiplied in this portion of the circulating system of Fishes in a very extraordinary manner. Thus, in the Stur- geon there are three series of semilunar valves, two at the commencement and one at the ter- mination of the bulb, the last being the strong- est and most perfectly formed. Those at the base are much thickened at their margins, which are attached to the parietes of the bulb by small chordse tendinese. The two lower valves are each made up of four semilunar f
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