[235] Zeiller (84). Phymatoderma is probably a horny sponge (vide p. 154).
[236] Newberry (88) p. 82, Pl. XXI. There are some large specimens of this supposed alga in the National Museum, Washington; they are undoubtedly of the nature of rill-marks.
[237] Vide Williamson (85).
[238] Dawson (90) p. 615.
[239] Salter (78) p. 99.
[240] Lapworth (81) p. 176, Pl. VII. fig. 7.
[241] Rothpletz (96).
[242] A term applied to a certain facies of Eocene and Oligocene rocks in Central Europe.
[243] Hall (47) Pl. LXVIII. 1 and 2, p. 261.
[244] Nathorst (83) p. 453.