Pl. bullæ. [L. = bubble.]
1. Pathol. A vesicle containing watery humour and causing an elevation of the skin.
1876. Duhring, Dis. Skin, 44. Bullæ are irregularly-shaped elevations of the epidermis, varying in size from a split pea to a goose-egg, containing a clear or opaque fluid.
b. Physiol. ‘The tympanic element of the temporal bone, when, as in the dog, it forms a large bubble-like appearance.’ Syd. Soc. Lex.
1872. Mivart, Elem. Anat., 106. In many Mammals … it forms a large inflated structure termed a bulla. Ibid. (1881), Cat, 62. The posterior surface of the auditory bulla.
2. Zool. A genus of mollusks, with thin and fragile shells, inhabiting deep water.
1847. Carpenter, Zool., § 917. The Bulla and Bullæa … have a small calcareous shell in which the spiral form begins to manifest itself.
1851. Mary Roberts, Mollusca, 201. The fragile shell of the solitary bulla is utterly inadequate to contend with either winds or waves.
