Shell bell-shaped, nearly conical, smooth. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 6. Cephalis nearly spherical, with a stout, straight, pyramidal horn of the same length. Thorax hemispherical. Abdomen gradually increasing in breadth towards the wide truncated mouth. Pores in all three joints nearly of the same shape, circular, regular, four times as broad as the thin bars.
Dimensions.—Length of the three joints, a 0.027, b 0.08, c 0.1; breadth, a 0.03, b 0.12, c 0.18.
Habitat.—Mediterranean (Messina, Naples, Nice, &c.).
2. Theoconus ægæus, Haeckel.
Eucyrtidium ægæum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 31; Mikrogeol., 1854, Taf. xxxv. a, xix. a, fig. 5.
Eucyrtidium ægæum, Haeckel, 1862, Monogr. d. Radiol., p. 329.
Shell flatly bell-shaped, nearly conical. Length of the three joints = 2 : 5 : 3; breadth = 1 : 7 : 8. Cephalis ovate, with a stout, straight, pyramidal horn of the same length. Thorax flat, bell-shaped. Abdomen with increasing breadth towards the wide truncated mouth. Pores in all three joints nearly of the same shape, regular, circular, three times as broad as the bars.
Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.03; breadth, a 0.016, b 0.07, c 0.08.
Habitat.—Mediterranean (Coast of Greece and Sicily), surface.
3. Theoconus zanguebaricus, Haeckel.