| 1 | Pinnae of normal bathyphylls (excluding youngest stages) deeply lobed. |
| 1' | Pinnae of bathyphylls (excluding youngest stages) crenate, not deeply lobed. |
| 2 | Lower pinnae of sterile acrophylls with stalks at least 6 mm long, often longer. |
| 2' | All pinnae of sterile acrophylls almost sessile. |
| 3 | Pinnae of bathyphylls deeply dissected to linear lobes. |
| 3' | Pinnae of bathyphylls less deeply dissected, ultimate lobes almost circular. |
| 4 | Ultimate lobes ⅓ mm wide |
| 4' | Ultimate lobes much wider |
| 5 | Fertile pinnae 3 mm wide |
| 5' | Fertile pinnae 10 mm wide |
| 6 | Most pinnae of sterile acrophylls, and of bathyphylls, very asymmetric at base. |
| 6' | All pinnae almost symmetric at base, both acrophylls and bathyphylls. |
| 7 | Largest sterile acrophyll pinnae to 9 by 2 cm; basal acrophyll pinnae with almost symmetric base, almost all other pinnae strongly asymmetric; fertile pinnae 4.5-5.5 cm long |
| 7' | Largest sterile acrophyll pinnae to 15 by 2.8 cm; basal acrophyll pinnae strongly asymmetric at base, distal ones much less so; fertile pinnae 20-24 cm long |
| 8 | Early stages with lamina on one side of midrib only; small transition bathyphylls with all pinnae on one side of rachis common; fertile pinnae to 20 cm by 3 mm, stalks to 5 mm long. |
| 8' | Earliest stages with lamina on both sides of midrib; normal and transition bathyphylls all with pinnae on both sides of rachis; fertile pinnae 5-7 cm by 5 mm, stalks 10-15 mm long |
