The projection of the echinus beyond the fillet of the abacus should be equal to the size of the eye. |
This is sometimes done, which proves that the energy required to perform the feat is not more than a healthy echinus can expend. |
At one end of the series we have the echinus with its rays all united in a box-like rigid shell. |
When a perpendicular surface is reached, the echinus may either ascend it or not, as in the case of the Star-fish. |
Its cylindrical mass tapering from a square base into the 12 wedges intended as the echinus or ovaio moulding below the abacus. |
It cannot be our task to follow all the points of organogenesis of echinus in detail. |