OCR Text |
Show 152 MR. F. E. BEDDARD ON THE VISCERAL [June 7, very long and thin, measuring, as has been mentioned, 2| inches each. While, therefore, the body of Platyurus is rather more than half the length of that of Hydrus, the kidneys of the latter are five times the length of those of the former genus. They do not, however, seem to me to be much, if any, greater in bulk, since they are extremely thin and narrow, Avhile those of Platyurus are wider in proportion to their length. Another difference shown by the kidneys of the two genera is the extent to which they overlap. In Platyurus the two kidneys hardly overlap at all, whereas in Hydrus the right anterior kidney extends alongside of the first two inches of the left kidney. There is thus a considerable approximation here towards symmetrical kidneys. § Lung. The lung-tissue is recognisable from twTo and a quarter inches behind the tip of the snout. It begins, therefore, very early in the neck. The lung-tissue begins gradually between the dorsal Text-fig. 27. A portion of the internal surface of the lung of Hydrus p latyurus. non-fused ends of the tracheal rings. This snake has therefore, as has been stated, a tracheal lung. The trachea, moreover, is open throughout into the lung, and forms in fact only a gutter along its ventral surface. The neck of this serpent is short, and therefore the tracheal lung is not of great extent; it appears to cease about half an inch in front of the heart, and therefore has not a course of more than two inches. A sudden widening at that point I take to be the commencement of the bronchial lun<r. There is no other differentiation that I can detect. The inner |