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Show 1 9 0 5 .] VASCULAR SYSTEM OF LACERTILIA. 4 6 9 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 hyoicl region. The right aorta gives off the subclavian 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, |
