Note 471 — Chapter IX · ON CONCRETIONS, SPICULES, AND SPICULAR SKELETONS
Reading edition
For figures of these crystals see Brandt, F. u. Fl. d. Golfes von Neapel, XIII, Radiolaria, 1885, pl. v. Cf. J. Müller, Ueber die Thalassicollen, etc. Abh. K. Akad. Wiss. Berlin, 1858.