1905.] VASCULAR SYSTEM OF LACERTILIA, 487 
bena are not jomed by ductus Botalli to the systemic arch. 
The left systemic arch in A. brasiliana is considerably larger 
than the right. 
The left anterior vertebral artery is not exposed for the whole 
of its course within the body-cavity. Shortly after its origin 
from the right aortic arch, and while its course is still oblique 
and towards the left side of the body, it is covered by a muscular 
layer, which is a continuation of the thick muscle covering the 
vertebral centra in the cervical region, and forming a soft cushion 
for the cesophagus to rest upon, and corresponding, I presume, to 
the longus colli. ‘This muscle (see text-fig. 69, p. 486), after 
crossing the left anterior vertebral artery as already mentioned, 
becomes more and more slender and disappears. It is important 
to note that it is not symmetrical, and that no corresponding slip 
covers the right anterior vertebral artery. This curvature of one 
artery at least by a muscular slip seems to me to have a bearing 
upon the homology of the arteries, 
The origin of these arteries from the right aortic arch, and the 
fact that one springs from the aortic stem in front of the other, 
is a distinct point of likeness to the subclavians of other Lizards, 
which give off an anteriorly running vertebral. The loss of the 
fore limbs and the increased importance of the neck for burrow- 
ing purposes might account for the disappearance of the main 
subclavian stem and the increase of its vertebral branch. The 
burrowing of the artery in question beneath the musculature to 
which I have referred is found in the case of the subclavian of 
Tiliqua*. 
There are three very slender wsophageal arteries arising from 
the aorta. They are followed by three gastric arteries, of which 
the last lies a little way behind the gall-bladder. The mesenteric 
arteries have been shown by Rathke vt to differ considerably 
among the Amphisbeenide. In the species examined by me 
there is a celiac artery followed by a common mesenteric; the 
intestine is also supplied by a posterior mesenteric which arises 
from the aorta among the renal arteries. 
The sper matic arteries arise just after the arteria mesenterica 
communis; the right is slightly in advance of the left. They 
both arise in common with an intercostal. On the left side an 
additional spermatic artery arises very close behind the main 
one. 
Behind the spermatic arteries a number of fine arteries supply 
the vas deferens. Of these I counted six on the left side, and 
there are about as many on the right. As a rule (five on the left 
side), these arteries arose directly from the aorta and indepen- 
dently of the intercostal arteries. 
The renal arteries differ in number on the two sides of the 
body. I counted four on the left and five on the right side. 
* Beddard, P. Z.S. 1904, i. p. 465. 
+ Abh. Ak. Wiss. Miinchen, ix. (1863). See also Hochstetter, Morph. Jahrb. 
xxvi. (1898). 
Proc. Zoou. Sec.—1905, Vor. II. No. XX XIII. 33 
