1905.1 



VASCULAU 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 mii-abile. The carotid, in 

 fact, ai'ises 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-fi^. 61. 



Heart and aortic trunks of 0-phisaurus, 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 fii-st 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 muscvilature, ramifying out beneath the scales. The 

 third branch goes to the hyoid 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, 



