1905. | VASCULAR SYSTEM OF LACERTILIA. ~ 469 
characterise other Lizards. As will be seen from the drawing 
(text-fig. 61), the artery is not merely a branch of the arch, but 
between the two is an abbreviated rete mirabile. The carotid, in 
fact, arises by three or four mouths, which at once unite to form 
the single vessel. This is not shown in a lateral view of the 
neck-arteries given by Rathke. 
One cannot but compare this with the carotid “ gland” of 
the Frog. 
Precisely the same mode of origin was shown on both sides of 
the body, so that we have evidently not to do with an asymmetrical 
anomaly. 
Text-fig. 61. 
Heart and aortic trunks of Ophisaurus, to illustrate mode of origin of 
carotid (c). 
Branches of Carotid.—Before the origin of the carotid artery, 
the carotid arch, as in other Lacertilia, gives off branches, which 
differ in detail from these other forms. The first to be given off 
is a branch to the thyroid on the right side; I did not notice a 
corresponding branch on the left side, and, as will be seen shortly, 
the right half of that gland receives its blood-supply from another 
source. The next trunk divides into three principal branches, of 
which the first supplies the sternal musculature and the adjoining 
parts, the next is a slender artery which runs under the skin and 
above the musculature, ramifying out beneath the scales. The 
third branch goes to the hyoid region. 
The right aorta gives off the swhclavian vessels before joining the 
left aorta. My observations upon these arteries agree with those 
of Rathke. They arise by a common stem from that aorta, which, 
