1. Pharyngeal gill slits are present.
2. Central nervous system is hollow and dorsal in position.
3. Nontochord persists in embryo or throughout the life.
4. Post- anal is present in embryo or adult.
5. Heart is ventral in position.
6. Hepatic portal system is present.
1. Pharyngeal gills slits are absent.
2. Central nervous is solid and ventral in position.
3. Notochord is absent.
4. Post anal tail is absent.
5. Heart is dorsal in position.
6. Hepatic portal system is absent.