| No secondary or interradial ribs are interpolated between the four primary. |
| Between these arise four interradial beams, which are united above by an upper square ring. |
| Lower ring octagonal, with eight peripheral adradial spines, and with four interradial centripetal teeth on the inside. |
| Three gates of the cortical shell roundish, on the inside with an interradial spine, little broader than the quadrangular arms. |
| Unpaired fins hyaline, with longitudinal rows of small black spots on interradial membranes. |
| Between the latter four interradial beams arise from the sides in pairs, and the two pairs are connected by a diagonal arch. |
