392 SURG. J. C. THOMPSON ON THE 
As it was not feasible to study the vertebral artery without 
injuring the air-chambers, this record was taken from another 
specimen (17 6, same locality), an adult female, with 243 gastro- 
steges and the heart apex at the 63rd g. The artery arises at 
the level of the 56th g. and courses superficially to the 23rd g., 
where it entersinthe median line. There are fourteen intercostal 
arteries arising as follows: I.—56, this arises quite in the anterior 
angle formed by the vertebral and the right aorta and enters 
in the median line; IJ.—56, enters to the left; III.-52, bi- 
furcates, and one fork enters on each side of the body ; TV.—50, 
bifurcates, both forks enter in the median line; V.—47, this and 
the rest of the branches are single and enter in the median line; 
VI-43; VII.-42; VIIL-40; [X.-39; X.-37; XI.-35; XII.- 
33; XIII—30; XIV.—27. 
In almost all serpents the intercostal branches of the vertebral 
artery enter the body-wall in the mid-dorsal line*. In this 
species the second and third branches offer two distinct types 
which are exceptions to this general rule. 
The right aorta, °5 mm. in diameter, joins the left, 1-5 mm. in 
diameter, to form the dorsal aorta at the 68th g. The intercostal 
arteries anterior to the kidneys enter the parieties to the right or 
to the left of the median line: I.-73 and II.-83 to left; III.-87 to 
right, and at the entrance it sends a branch to the left side which 
bifurcates, sending one branch into the parieties and the other to 
the peritoneal muscle. In the lumbar region the intercostal 
arteries enter as follows:—At the 199th, 203rd, 204th, and 
206th g. to the left. At the 208th g.a pair, one from each side 
of the aorta, and entering on either side of the vertebral column. 
At the 215th g. a single artery enters to the left. At the 215th 
and the 218th g. the vessels are paired. At the 226th g. the last 
artery is single and enters to the left. 
The right spermatic artery arises at the 167th g. and enters 
just anterior to the middle of the gonad. ‘The left arises at the 
181st g. and enters the middle of the organ. Just posterior to 
each testis there is an artery arising from the aorta which enters 
the cord. There are five renal arteries on the right side. They 
arise as follows: I.-203, courses to the rear for about one gastro- 
stege, while the remainder enter nearly directly; II.-205; 
II1—208; IV.-215; V.—222. The left kidney receives six 
arteries as follows: I.-207; II.-209; III.-212; IV.-217; V.-219; 
VI-222. 
The anterior vena cava at the 40th g. is looped to form an 
S-shaped curve, parallel to the median plane, and with the re- 
current limb measures 6 mm. This suggests the provision for 
the lengthening of the vein when the neck is inflated. 
In the female (No. 17 6) the gall-bladder is 14 mm. in diameter, 
the pancreas 18 mim. long, and the distance between the two 
organs 6°5 mm. 
The hepatic duct divides into about half a dozen tubes of un- 
* Beddard, P.Z.S. 1904, vol. i. p. 368. 
