[177]

Schneider, Beitr. z. vergl. Anat. u. Entwickl. Wirbelth., Berlin, 1879, p. 51; also Gadow, op. cit. p. 196.

[178]

Smith Woodward, Brit. Mus. Cat. Fossil Fishes, Pt. i. 1889, p. xvii.

[179]

Hasse, Das natürliche Syst. d. Elasmobranchier; etc., Jena, 1879, p. 30, et seq.

[180]

Gadow, op. cit. p. 194; Ridewood, Journ. Linn. Soc. Zool. xxvii. 1899, p. 46.

[181]

Günther, Phil. Trans. 161, 1872, p. 526; Wiedersheim, Morph. Studien, Jena, 1880, Pt. i. p. 65; Gadow, op. cit. p. 198.