Dimensions.—Major axis 0.12, minor 0.08; pores 0.06 to 0.012, bars 0.003; main axes of the medullary shells 0.05 and 0.025.
Habitat.—Indian Ocean, between Socotra and Ceylon, surface, Haeckel.
8. Prunulum fenestratum, Haeckel.
Actinomma fenestratum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 94, Taf. iii. fig. 2.
Cortical shell thick walled, rough, with irregular, roundish pores, once to three times as broad as the bars; twelve to fourteen on the half equator. Proportion of the two axes = 9 : 8. Both medullary shells ellipsoidal. (The pores in Stöhr's description are by mistake called "regular"; in the figure they are very irregular, as also in the fossil specimens observed by myself. Between the cortical pores arise very short irregular thorns.)
Dimensions.—Major axis 0.12 to 0.15, minor 0.1 to 0.12; pores 0.003 to 0.01, bars 0.003; main axis of the outer medullary shell 0.07 to 0.09, of the inner 0.03 to 0.04.
Habitat.—Fossil in the Tertiary rocks of Sicily; Grotte, Stöhr, Caltanisetta, Haeckel.
9. Prunulum pyrenium, n. sp.
Cortical shell very thick walled, smooth, with large irregular, roundish pores, three to four times as broad as the bars; six to eight on the half equator. The bottom of each funnel-like pore is closed by a thin siliceous membrane, perforated by three to five irregular roundish pores. Proportion of the two axes = 4 : 3. Both medullary shells ellipsoidal. (Closely resembles Stylatractus sethoporus, Pl. [17], figs. 2, 3, but is devoid of the polar spines.)
Dimensions.—Major axis 0.16, minor 0.12; pores 0.015 to 0.02, bars 0.005; porules 0.01; main axes of the medullary shells 0.07 and 0.03.