Holm, Morph. Jahrb. xxix. 1901, p. 365.
The sacci probably secrete the fluid contents of the ventricles.
Haller, Morph. Jahrb. xxvi. 1898, p. 345.
Goronowitsch, Morph. Jahrb. xiii. 1888, p. 427.
Burckhardt, Das Central-Nervensystem v. Protopterus annectens. Berlin, 1892.