| 1. Preoral organ and preoral lobe |
0, fused; 1, separate |
| 2. Position of the preoral organ |
0, lateral to the mouthhook; 1, anterolateral to the mouthhook; 2, anterior to the mouthhook |
| 3. Posterior margin of the oral ridges |
0, entire to serrate; 1, entire to emarginate; 2, at least some dentate; 3, all or most fringed |
| 4. Accessory plates |
0, present, bordering each oral ridge; 1, anteriorly absent, but medially and posteriorly bordering each oral ridge; 2, completely absent |
| 5. Posterior margin of the accessory plates |
0, entire to serrate; 1, entire to emarginate; 2, dentate; 3, fringed |
| 6. Vertical comb-like processes |
0, absent; 1, present |