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passes forward on the ventral wall of the trachea almost to the larynx 
This is possibly the vessel which Mackay thought was the posterior- 
remnant of the ventral carotid. 
The common carotid (ec. c.) gives rise to three branches between 
the innominate (in. a.) and its bifurcation into external and internal 
carotid vessels. Following the common carotid forward, the first of 
these three branches springs from the lower side feeding the ventral 
wall of alimentary tract and trachea. It is very small and runs only 
for a short distance. The second branch (arteria colli collateralis) 
arising from the common carotid varies in its point of origin. In 
Fig. 6. Camera sketch of dissection of the injected arterial system of the left side 
of a chick embryo incubated about thirteen days, showing the arteries of the head and 
neck region. X about 8 diameters. 
some specimens it arises as a branch from the cervical (cer. a.) feeding 
the thyroid body, crop and ventral wall of the cesophagus; in other 
specimens it arises from the common carotid (e.c.) as shown in this 
figure. When present as a branch from the common carotid no similar 
vessel is present as a branch from the cervical (cer. a.) and vice versa. 
It may, also, vary in point of origin on the two sides. The third 
branch from the common carotid is the stalk of the cervical-vertebral. 
Soon after leaving the common carotid it breaks up into the cervical 
artery and the vertebral proper. The cervical (cer. a.) follows the 
vagus nerve forward to the anterior third of the neck where it turns 
dorsally and feeds the superficial parts posterior to the base of the 
skull. The vertebral proper (ver. a.) after giving off a branch which 
