Two dorsal portions of this region, which are regarded by Masterman as lateral notochords, appear to me to represent the dorsal part of the pharynx of Ptychodera.
The diameter of a single individual removed from its tube is given by Fowler as .123 mm.
See, however, Conte and Vaney, C. R. Ac. Sci. 135, 1902, pp. 63, 748.
Pp. 450-462.
Quart. J. Micr. Sci. xl. 1898, p. 281; xliii. 1900, p. 375; xlv. 1902, p. 485.