According to this view it may be inferred that all vertebrate animals with true lungs are descended by ordinary generation from an ancient and unknown prototype which was furnished with a floating apparatus or swim-bladder.
Ikusmolde honen arabera, inferi daiteke benetako birikak dituzten ornodun guztiak, flotatzeko aparatu edo igeri-maskuria zeukan antzinako prototipo ezezagun batengandik datozela ugalpen arruntez.