In the Thecosomata, the Cymbuliidae « …have the intermediate fin [like in Cuvieridae] but the shell is only of a firm gelatinous substance. They have two eyes and two tentacles. The shells are variable in shape, but generally somewhat resemble a slipper. » – J. E. Gray: Synopsis of the contents of the British Museum p.144 of the 42nd. edition.
Cymbulia Péron & Lesueur, 1810:
« Two tentacles; a retractile proboscis; two eyes; the gills as a very thin network on the surface of the two lateral fins. All the body of the animal housed within a gelatinous-cartilaginous test. » – Péron & Lesueur: “Histoire de la famille des Mollusques Ptéropodes. Caractères des dix genres qui doivent la composer.”, Annales du Muséum National d’Histoire Naturelle vol. 15, Paris 1810, p.66.
