[12]

Die rhabdocoelen Turbellarien des Süsswassers. Jena 1848.

[13]

Monographie d. Turbellarien. I. Rhabdocoelida, 1882. Die Acoela, Leipzig, 1892.

[14]

"Die Polycladen," Fauna u. Flora d. Golfes v. Neapel, Monogr. XI. 1884.

[15]

Phil. Trans. 1874, p. 105.

[16]

Since no food, but only the pharynx, passes through this "mouth," the term is unfortunate. Moreover the true mouth is the aperture placing the stomach in communication with the pharynx (Fig. 5, gm).