Dimensions.—Major axis of the cortical shell 0.15 to 0.2, minor axis 0.1 to 0.14; pores 0.006 to 0.012, bars 0.03; diameter of the medullary shell 0.04.
Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.
9. Druppula elliptica, Haeckel.
Haliomma ellipticum, Stöhr, 1880, Palæontogr., loc. cit., p. 88, Taf. i. fig. 11.
Cortical shell thin walled, rough, or thorny, with irregular network; proportion of the axes = 3 : 2. Pores subcircular or irregular, roundish, about as broad as the bars; ten to twelve on the half equator. Medullary shell half as broad as the cortical shell, irregularly polyhedral (with crooked beams in its interior).
Dimensions.—Major axis 0.15, minor 0.06; pores and bars 0.006; diameter of the medullary shell 0.03.
Habitat.—Fossil in the Tertiary rocks of Sicily: Grotte (Stöhr), Caltanisetta (Haeckel).
10. Druppula prunum, n. sp.
Cortical shell thick walled, smooth, with irregular network; proportion of the axes = 5 : 4. Pores subcircular or irregular, roundish, three to four times as broad as the bars; seven to eight on the half equator; every pore is closed at the bottom by a thin membrane, perforated by four to six irregular pores (like Stylatractus sethoporus, Pl. [17], fig. 3). Medullary shell spherical, one-third as broad as the cortical shell.
Dimensions.—Major axis 0.2, minor axis 0.16; pores 0.03, bars 0.01; small enclosed porules 0.01; diameter of the medullary shell 0.05.