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Show 1 9 0 6 .] RESPIRATORY SYSTEMS IN THE OPHIDIA. 5 1 5 entirely to the peritoneal sac in which the liver lies. They ramify over the walls of this sac, and do not plunge beneath it to enter the substance of the liver. This recalls the branches of the umbilical vein of Birds, many of which ramify in the umbilical ligament which bears the vein. It may be that these veins are also present in Boa diviniloqua; indeed, one would assume that they were present but they were not visible. With regard to the Arterial System, I call attention here to two points only. Firstly, in both Boa diviniloqua and B. constrictor each kidney is supplied by a single renal artery, which enters the kidney at the anterior end. These additional instances increase the probability that the Boidse in general are to be characterised by this anatomical fact. Though it has to be admitted that the number of Boine genera at present examined from this point of view is not large, only one exception has been met with, viz. Eryx jaculus, in which snake there are sometimes, but not always, two renal arteries to each kidney. I may take this opportunity of increasing the list of Boidfe known to possess only a single renal artery to each kidney. I have recently had the opportunity of dissecting an example of jPython molurus measuring over 9 feet in length. In this snake the right kidney measured eight and a quarter inches in length, and the left kidney was nearly as long. In spite of this length, each kidney had only one renal artery. In Python regius, which is a smaller species but still of considerable size, there was no doubt about the fact that each kidney had only a single artery. In an example of Enygrits car hiatus* the left kidney at any rate had but one renal artery. I did not examine the right. The second point concerns the intercostal arteries, which resemble those of Eunectes and Eryx f and Python spilotesi, and not those of Python sebce and Corallus. Each pair of arteries, in fact, does not issue directly from the aorta; but several pairs are given off from a common trunk which runs longitudinally for varying distances in different cases. These trunks arise at varying intervals from the aorta. Lungs.-In Boa diviniloqua there are two lungs which are, of course, unequal in size, though both are vascular. The trachea in the neck-region has incomplete rings, which are united posteriorly by a tract of membrane. There is, however, no trace, that I could discover, of a tracheal lung. The lungs, both of them, end in a very distinct line at the point of opening into them of the bronchi. The vascular and red membrane ceases abruptly. A point in which the genus Boa differs from Python is in * I owe the opportunity of examining this snake to Dr. C. G. Seligmann. I may take this opportunity of remarking that the kidneys are very small, as in Eryx, measuring respectively 16 and 17 mm. The right kidney lay 72 mm. from the cloaca. The snake measured 19f inches from the tip of the snout to the cloaca. f Beddard, " Anatomy of Boidae," P. Z. S. 1904, vol. ii. p. 108. J Beddard, P. Z. S. 1904, vol. i. p. 362. This species has been placed in a separate genus. |
