| Main Ref. | Hart, J.L., 1973 |
| Appearance refers to | |
| Bones in OsteoBase |
| Specialized organs | |
| Different appearance | |
| Different colors | |
| Remarks |
| Striking features | |
| Body shape lateral | eel-like |
| Cross section | |
| Dorsal head profile | |
| Type of eyes | |
| Type of mouth/snout | |
| Position of mouth | |
| Type of scales | |
| Diagnosis |
Caudal fin narrowly rounded but not distinguishable from dorsal and anal fins. Pelvic fins minute. |
| Ease of Identification |
| Lateral Lines | Interrupted: No |
| Scales on lateral line | |
| Pored lateral line scales | |
| Scales in lateral series | |
| Scale rows above lateral line | |
| Scale rows below lateral line | |
| Scales around caudal peduncle | |
| Barbels | |
| Gill clefts (sharks/rays only) | |
| Gill rakers | |
| on lower limb | |
| on upper limb | |
| total | |
| Vertebrae | |
| preanal | |
| total |
| Attributes | continuous with caudal fin |
| Fins number | 1 |
| Finlets No. | Dorsal 0 - 0 |
| Ventral 0 - 0 | |
| Spines total | 0 - 0 |
| Soft-rays total | 94 - 105 |
| Adipose fin | absent |
| Attributes | other (see remark) |
| Fins number | 1 |
| Spines total | 0 - 0 |
| Soft-rays total | 83 - 90 |
| Pectoral | Attributes very large , lobe-like |
| Spines 0 | |
| Soft-rays 17 | |
| Pelvics | Attributes aberrant |
| Position thoracic before origin of D1 | |
| Spines 0 | |
| Soft-rays 3 - 3 |