etc.--though they may also send blood through the above-mentioned connectives to the brain and dorsal regions of the skull. The _primary carotid_, capr, as was noted above, makes a curve to the left after leaving the heart and then passes back to the median plane, where it may be seen lying against the ventral side of the neck muscles and dorsal to the œsophagus; in this place it gives off a series of unpaired _cervical_ arteries, Fig. 62, ce, each of which almost immediately divides into an anterior and a posterior branch, that carry blood to the cervical vertebræ. At the base of the skull, in the region where it is united by the first connective, x, with the collateralis colli, as described above, the primary carotid divides into two similar branches, called by Bronn the _common carotids_, cm. The distribution of these two vessels is symmetrical, so that only one need be described. While the collateralis colli, as has been said, carry blood chiefly to the tongue and lower jaw, the common carotids supply the cranium and upper jaw. Soon after its formation by the division of the primary carotid, the common carotid is joined, as noted above, with the collateralis colli of that side by the connective, x; since the common carotid and its branches all lie dorsal to the collateralis colli and its branches, the connectives x and x¹ extend in a more or less dorso-ventral direction. The two common carotids, almost completely surrounded by bone, in passing cephalad sweep first laterad, then mediad, so that they together form almost a complete ellipse, as seen in Fig. 62; there is, however, no apparent connection between them at the anterior region where they lie so close together. A short distance cephalad to the connective x the common carotid is connected laterally, z, with a rather complicated plexus of vessels lying at the base of the skull; it is through this plexus that the common carotid is connected with the collateralis colli by the second connective, x¹.