1906.] RESPIRATORY SYSTEMS IN THE OPHIDIA. 515 



entii'ely to the peritoneal sac in which the liver lies. They ramify 

 over the walls of this sac, and do not plnnge beneath it to enter 

 the siibstance of the liver. This recalls the branches of the um- 

 bilical vein of Birds, many of which ramify m 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 diviniloqiuc 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 Boidag 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 

 jacttlus, in which snake there are sometimes, but not always, two 

 renal arteries to each kidney. 



I may take this opportunity of increasing the Hst of Boidas 

 known to possess only a single renal artery to each kidney. I 

 have recently had the opportunity of dissecting an example of 

 Python 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 regiics, which is a smaller species but still of con- 

 siderable size, there was no doubt about the fact that each kidney 

 had only a single artery. 



In an example of E^iygnos carinatus* 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 Eanectes and Eryx'f and Python spilotesX, and 

 not those of Python sebce and Corallus. Each pair of arteries, in 

 fact, does not issue dii^ectly from the aorta ; but several paii-s are 

 given off from a common trunk which runs longitudina^Uy for 

 varying distances in different cases. These trunks arise at varying 

 intervals from the aorta. 



Lungs. — In Boa diviniloqtca 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 postei"iorly 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 Hne at the point of opening into them of the bronchi. 

 The vascular and red membrane ceases abruptly. 



A point in Avhich the genus Boa difiers from Python is in 



* I owe the opportunitj' of examining this snake to Dr. C. G. Seligmanu. 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 19j inches from the tip of the snout to the cloaca. 



t Beddard, " Anatomy of Boids," P. Z. S. 1904, vol. ii. p. 108. 



X Beddard, P. Z. S. 1904, vol. i. p. 362. This species has been placed in a separate 

 genus. 



