Final answer:
The circular molding under the cushion of an Ionic Capital is called the cymatium, also known as the Echinus. It is usually carved with an egg-and-dart pattern and adds decorative detail to the capital.
Step-by-step explanation:
The circular molding under the cushion of an Ionic Capital, between the volutes, is called the cymatium. It is usually carved with an egg-and-dart pattern. Another term for it is the Echinus. The cymatium adds decorative detail to the capital and is a notable feature of the Ionic order.