[75] Gegenbaur. Grund. d. Vergleich. Anat. p. 210. See also Dr. M. S. Schultze, Beiträge zur Naturg. der. Turbellarien. 1851. Pl. vi. fig. 1.
[76] Monographieder Moneren, p. 10.
[77] See Kauffmann, Ueber die Entwickelung and systematische Stellung der Tardigraden. Zeits. f. Wiss. Zool. 1851, p. 220.
[78] It is true that among the Insecta generally the first stages of development differ in appearance considerably from those above described; those of Platygaster, as figured by Ganin (ante Figs. [17-22]), being very exceptional.
[79] Monograph of the Gymnoblastic or Tubularian Hydroids, by G. J. Allman, Ray Soc. 1871, p. 86.
[80] Mém. sur les Vers Intestinaux, 1858.
[81] Natural History Review, 1861, p. 44.
[82] Ann. des Sci. Nat. 1847, p. 90.
[83] Fauna littoralis Norvegiæ, pl. viii.
[84] Trans. of the Microsc. Soc. of London, 1851.