CIRCULATORY ORGANS. 297 
tion. Connected with the carotid arteries are the carotid glands (fig. 304). In 
| the larval stage each consists of a network of blood-vessels—a rete mirabile— 
| between the afferent branchial and the carotid artery, but in the adult this degener- 
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ates into a small muscular organ containing sympathetic cells (p. 165), at the 
base of the carotid. 
The postcava is well developed and the epigastric veins unite to form an anterior 
