Thomas Wyatt, A Manual of Conchology
“ Bulla. The Bubble. Eleven species. The great confusion that existed in this genus, as classed by Linnæus, has been elucidated by the division and classification of Lamarck. This genus derived its name from the resemblance which some of the smaller species have to a bubble of water. Its shells are found in almost all parts of the world.Shell external, oval, involuted; aperture very large, open the whole length of the shell, and generally wider at the base; outer edge sharp and smooth; summit umbilicated. ”
