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Ridewood, Anat. Anz. xi. 1895, p. 425.

[278]

Garman, Bull. Mus. Comp. Zool. Harvard, xii. 1885, p. 1; Günther, Challenger Reports, "Zool." xxii. 1887, p. 2.

[279]

In the Ammocoetes stage the gill-sacs open directly into the larval pharynx, which is retained as the branchial canal, the oesophagus of the adult being an independent and later formation.

[280]

Dohrn, Mitth. Zool. Stat. Neapel, vi. 1886, p. 49.

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Shipley, Quart. J. Micr. Sci. xxvii. 1887, p. 350.